How about some new heads? Another intake probably won't make the power jump you want without the help of nice flowing heads. I don't think working the 289 heads will get you where you want either. Was your shortblock a stock rebuild?
the cam is new, and matches up to performer heads (i dunno bout the rpm heads) but would my cam be good with the gt40 heads? the cam is not coming out.
I have the performer on my vert with AFR's, works good even with the stock cam. Spend the $$ in some good heads and try port matching the performer to the head and you'll pick up a bunch. And spend a little more time on the dyno tweaking the timing, 3-4* timing changed my HP by 10-20...
ok i got to talking with a guy who has a 66 and hes putting down some serious power. i told em i dynoed and got 150 horse and he looked at me. he asked about the engine and he said the heads was where its killing the engine. not letting enough air in. he reccomended a place here in town that will work my heads and put in larger valves (said they were chevy valves) something like 194/205 valves.
I picked up a set of dart windsor jr aluminums for $700 for the pair.
A decent set will run you ~$1000 for a fully assembled pair. Pretty much all $700 pair alums need work (Take off GT-40s X/Y, Superflow heads etc . . .)
I have a set of 66 289 heads that have been ported and have the chevy valves in them. They dont flow even close to what my AFR 165's do. Save the $$ up for some name brand alum heads. Skip the ones you havent heard of, usually more $$ to get them right and it's not a part that you want to go cheap on.
You can't port factory heads to flow as well as good aftermarket ones. You hit water jackets. Modern aftermarket heads are designed with 21st century technology, not late 50s technology.
If you want to make power, quit screwing around with band-aids and get some decent heads.