Welcome! I had an 85 for about 10 years, sold her recently. I converted to intercooled 87 stuff, and if you are looking for big HP, that is probably where you would be headed. There are some guys going pretty fast with 85 guts, but it is more challenging. Look at Razors alky kit, convert to 87 ECM, get a Turbotweak chip, ported intake from GBodyparts, ported heads, electric fan and rad kit from Alradco, ported throttle body, cold air kit, etc, etc. Hell, its only money!
Let me know if you decide to convert to 87 IC'ed. I may have 95% of what you need in my garage. (you may have seen me on "Car Parts Hoarders", a new show on the Discovery Channel)
Again, welcome! Post pics, plans, and questions. And plan on making it to Buicks at Bates Car show June 1st. You won't want to miss it!