Here is some rebuilding info to beef up this tranny:

http://www.drwtransmission.com/thm_200-4r.htm

Because these are the numbers on a stock 87 Monte Carlo SS:

Q: How much horsepower and torque is the stock SS Engine rated at?
1984 through 1988:
180 HP @ 4800 RPM (flywheel)
225 ft/lbs @ 3200 RPM
All horsepower (HP) readings are S.A.E. Net, measured at the flywheel of the engine, as installed, with a complete exhaust system and all accessories attached. This figure is measured on an engine dyno. It is not the horsepower at the rear wheels

I don't know what engine you are running but my stock 1968 350 numbers:
265 HP @ 4500
355 ft/lb @ 2800

Thats a 85 HP and 130 ft/lbs over the standard Monte SS and another reason to beef up the 200-4r.

I'm currently running one in my 68 Firebird and it's great (actually drove it today). I went with a professionally built one:

http://www.2004r.com/trans/level2.shtml

because I didn't want to try to rebuild it myself to handle the extra power.

G.J.
68 350 Coupe