first things first, what is your goal with this car - is it a drift car, drag car, circuit car etc -
do you want 300 hp 400 hp or 500+ hp ?
if you only want 300 hp DO NOT waste your money building your engine to that extent, a head gasket and head studs will last you years on only 300hp
if you want to make 400hp reliably you can build the bottom end using STOCK crank, upgraded bearings, eagle rods and which ever pistons you choose, stay stock size or go .20 over, the higher you go the more compression and less OEM reliability -
in the head, there will always be more work than what you think is needed, cams, valves, springs and retainers are a must if the engine is apart -
i would budget for at LEAST 4500 dollars to build your engine, i am currently well over that with similar modifications, if your going to re use stock lifers, and stock guides, etc - its not really saving you anything to leave them oem -
here is a quick breakdown of a parts list where you can get an idea of in your hands pricing -
Head downward -
HKS RAS 150
BC Cams 300
BC Springs and Retainers 180
BC SS Valves 150
Head work? 400 to 2000
Pistons 400 to 1000 to 2000
Rods 350 to 1000
Bearings 150 to 400
ARP Head Studs 120
ARP Main Studs 160
ARP Flywheel bolts 90
Gasket rebuild kit 180
OEM Water pump 80
OEM Oil Pump 235
New Chain or Aftermarket 160 to 500
Greddy Oil Pan 450
ATI Crank Pulley 450
Spark Plugs 50 to 150
Splitfire Coil Packs 450
Block Machine work? 500 to 2000
Misc Machine work Cleaning And Assembly 500
Im sure i am missing many parts but this gives you an idea of how expensive building an engine properly can get.
This set up can easily handle 500HP as well but i do not know how you will get it there without all the other supporting modifications, which will inevitably take you well into the 8 to 10 thousand dollar range…