318 Input and help...please

As far as a fuel pump i always liked the high end carter mechanicals, though you may have to regulate the pressure some. There are some reasonably priced balancers that are SFI approved, summit even offers one. http://www.summitracing.com/parts/SUM-C4277/
As far as the carb, i'd go Holley DP all the way. A Mdl. 4779 (750) has a resonable price, good used one even a option. I'll throw out a guess on hp at 425, but you're definetely gonna have to spin it. Down the road the only issue i can see is you'll probably want to step up the converter some..........Good luck.