Greetings, and welcome to the SCA!
The best resource for names that I have found is the Academy of St. Gabriel. You can submit a question to them, but they have been on vacation for some time. However, they have several articles as well as their past letters that you can consult.
As for Moira MacDonald, here is what the Academy has spread across several of their archived letters:
<Moira> is an English phonetic spelling of <Ma/ire>, the Irish form of <Mary>. (The slash represents an accent over the previous letter). We haven’t found evidence that <Moira> was used during the Society’s period, so we recommend that you avoid it.
-1050, Academy of St. Gabriel [Link]
<Moira> is an Anglicization of <Ma/ire>, the Irish form of <Mary>. Unfortunately, this Anglicization appears to have been invented after the SCA period. We've found no evidence that it was used in period, and <Ma/ire> itself was extremely rare as a personal name in Ireland until the 17th century: there are a few examples from the
15th and 16th centuries, and the earliest known instance is an isolated 14th century example. The Irish considered the name too sacred for ordinary use; instead they used <Ma/el Muire> 'devotee of Mary'.  (The slash stands for an acute accent over the preceding vowel.) This was pronounced roughly MA VOOR-(y)eh, where the <y> in parentheses stands for a very, very lightly pronounced y as in <yes>. -1440, Academy of St. Gabriel [Link]<Muirenn> is a fine Gaelic feminine name for your period . It is pronounced somewhere between MOOR-en and MOOR-yen, where the OO is pronounced as in <moo>. This name is not related to <Moira>, a modern
English phonetic spelling of <Ma/ire>, which is the Gaelic form of <Mary> . The slash in that name indicates an accent on the preceding letter.
-1709, Academy of St. Gabriel [Link]
For MacDonald, in period this simply meant “son of Donald,” not “part of the MacDonald clan” [Link – St. Gabriel]
The SCA Heraldry website also has an article on feminine Scottish names [Link].
I’d also encourage you to consult the herald’s table at an event, or get in touch with your local/regional/kingdom herald for help. There are “book heralds” and “court heralds” – you want one of the former for help with research. I’m not a herald – I’m just a librarian. 😀
You could also post to the SCA Heraldry Chat Facebook Group to get some guidance as well.
All of that being said, don’t feel too pressured to have a surname nailed down before you go to your first event. A first name is enough – I still haven’t submitted my paperwork for my “more period than locative” surname. People will generally call you by whatever you introduce yourself as, and first names are always easier to remember (at least in my experience).
Good luck to you, and welcome!
So what do we consider late period? The latest I could find was late 16th century, but the majority was 14-15th.
For search terms (in the image description field of your favorite manuscript database, try “genealogy.” That seems to pull up the most results.
Here are some highlights:
King’s 395, ff. 32v-33: Genealogy of the kings of England
c. 1511, with additions before 1553
Lansdowne 204, f. 196: Royal genealogy
Harley 7353: Genealogy of Edward IV
Harley 7026, f. 4 – Genealogy of the Holland family
Harley 838, f. 12v-13 and 38
2nd half of the 15th century
Harley 318, f. 6r: Genealogy of the Kings of England
3rd quarter of the 15th century, after 1445 and before 1461
The Bodleian has a lot of great stuff too, which you can find here: [Link] The earliest looks like it is from the end of the 13th century.
Highlights from the Bodleian:
MS. Bodl. Rolls 5, view 36: Genealogy of the Kings of England to Richard III. Chronicle of the Percy Family to 1485.
[Link] – hopefully this will work. Linking to specific items in the Bodleian is always… interesting.
There are a lot of pages from this one. Totally cool.
MS. Ashmole 845, f. 074r. Genealogy of the Kings of England, from Edward I to Henry VIII.
MS. e Mus. 42, fol. 031v-032r: Genealogy. Edward I to Edward IV
Harley 647, f. 5v
Illustration of the swan of the constellation Cygnus, with text or scholia within the figure of the constellation.
from Aratea, with extracts from Hyginus’s Astronomica in the constellation figures, 9th century France
Frith, J., Appleby, R., Stacey, R., & Heron, C. (January 01, 2004). Sweetness and light: chemical evidence of beeswax and tallow candles at Fountains Abbey, North Yorkshire.Medieval Archaeology, 48, 220-228.
Sweetness and light: the mysterious history of the honeybee, by Hattie Ellis, 2010
Medieval Candle-Making Class, by Hl Cathus the Curious (Keith Roberts)
Video has a comment re: using beeswax in molds.
All Things Medieval: An Encyclopedia of the Medieval World (2 volumes) by Ruth A. Johnston, 2011.
Link to page discussing beeswax candles
Stairway to Heaven: The Function of Medieavl Upper Spaces by Toby Huitson, 2014
Link to page about lighting; cites beeswax candles c. 1250.