450 injectors
.20 over unless your block is good for stock bore
Stock rods and pistons or vitara/eagle if you really want too.
suggest headstuds
T3 turbo like super 60 or t28 disco potato
yes stock head is fine

Honestly you can make 250 stock its all about tuning and be reliable. Good luck
but if you do go this route I suggest headstuds.