IN genteral try multipliy the HQ skills by 2.5 to get MRQ skill scores. So a mastery is worth around 50%.
Stats are a bit tougher.
Try 1.444 for STR & SIZ. THat is pretty close. Or here is a close appoximation of Large & Small to SIZ. It probably holds up reasonable well for STR.
LArge
12 White Tail Deer (14-15)
15 Ostritch (20)
18 Lion (26)
2W Pony (29)
5W Horse (32)
10W Rhino (43)
18W Elephant (51)
2W2 Elephant (55)
5W2 Dream Dragon (70)
18W2 Brotard (70+)
Small
10 Typical Dog (4)
12 Small Dog (3)
15 Cat (2)
18 Small Bird (1)
5W Mouse (0-1)
10W Shrew (0-1)
5w2 LArge Beetle (0-1)
15W2 Gnat (0-1)
If you have RQ3 or RQ2 stuff, you can probably get stats for most of the creatures there instead. You can also get some good alnalogues. FOr isntace is someting has a SIZ 1 point smaller than a horse, wrting it up a SIZ 30 probably won't be far from the mark.