dO WHAT i DID.........lol!!
I am at 451 hp/430 tq........New Alum. Cobra/truck (thicker cyl. walls) J&E Pistons, Manley Rods, etc........50lb injectors (600$)
Stage 2 ported heads, Intake (1,200$), Plenum (trick flow), 75mm TB, MSD ignition kit (600$), 3:73's, Griffon alum. radiator, Changed fuel system to Return style with Weldon Pump (must purchase 86-95 Fox body Sumped Gas tank), Vortech SC & Aftercooler, plus tons more. Too much to list........But basically if you want 450-500 hp your gonna have to spend approx. $15,000+........Even with Nitrous........
There are a lot of little things and changes that have to be upgraded that end up eating $$$$$$....
I am now having to get a Tremec TKO600 & Axels cause the stocj T45 tranny won't handle my HP much longer...so there's another $8,000 with labor & parts..........
But yes, I would recommend getting a "New" block (aluminum) and building that up....approx...3,500$ with internals).
Replace all stock parts (plenum, TB, intake, etc...) with aftermarket...
You will be using a lot of fuel too...I drive 60 miles total a day to and from work........I use a 1/2 tank of gas everyday!!!!