estimate on hp for a build i didn't do

i just picked up a '64 impala with an sbc and 700r in it. here's what i know. it's an '87 L 98 motor bored to a 355 with an edelbrock performer intake and a rochester quadrajet with the 87 corvette heads, headers and 336 rear end gears. the new cam was stock for the motor supposedly and nothing special was done to the heads.
i really haven't laid into it yet because i didn't build it. from a dead stop the back tires are skipping with just maybe half throttle being applied.
sorry i got long winded. my question is, can anyone estimate the horsepower this set up might have based off of what i know? i know people have done the tpi to carb conversion before and i've read that you actually give up a little torque on the bottom end.
i'm really just looking for a cruiser and something peppy on a short run. not interested in top end speed because that sled doesn't really need to fly, just needs to get to 100 kind of quick.

This would be difficult to guess at since the L98 Corvette engine was rated at around 240hp using TPI which was a 30% increase in hp over carbs and 20% over the crossfire setup, with your overbore and headers increasing the hp and the lack of the TPI, not sure how to vary the hp rating for you setup. I only commented here to provide info/numbers to at least think about.