[84LX89GT]

Keeping the stock intake would be a major bottle neck if you're getting new heads and improved intake tract. One of the major problems of the stock intake is that cylinders 1 and 5 get less air flow than the other cylinders, so those cylinders automatically produce less power than the others at WOT.

You would probably gain another 20-25 horsepower by changing it out for an aftermarket manifold. the stock manifold is horrible. I had a stock manifold opened up to 70mm for the throttle body i had and i noticed a HUGE differance when i switched to the trick flow manifold. the power band went from weezing at 4500 to pulling to 5500. That's with the stock heads and not gasket matched, i'm changing my heads soon as well as getting a new camshaft, and i'm sure that after i gasket match it, i'll be at or above 300 hp. since you're in there, just save up the $400 or $500 for an intake manifold, although you'll still make more power than stock if you just put on the heads.