Re: Thoughts about this trade...
Assuming you have to sell it, the missing info is:
A) how much are the two guitars worth? A nice condition RG8527 would probably fetch about $1500 USD minimum. here was one in the UK advertised at £1295GBP ($2600) for ages on the bay, I think it may have eventually sold after months, but usually they go for more like $1500 - $1700 USD. (that's my experience looking at the UK listings anyway)
Maybe someone else on the board can help with estimated value of the UVMC? Then it's just a case of seeing whether the swap is good value.
B) Are you happy with the change in specs?
RG8527 - ball end fret finishing, J-custom neck joint, nice neck pickup plus whatever bridge you've thrown in there, amazing quilted top, mahogany sound
UVMC - prestige style fret finishing, old-style neck joint (I think), Blaze pickups (I think), basswood sound, middle pickup
If you need to buy a replacement 7 string, you could maybe look at a used RG7620 or RG1527 and free up more money?