You can usally buy stock style cast pistons in a couple of differnet shapes for about the same price. Try to find some cheap pistons that will give a good cr for some good power.
One main factor alot of ppl over look with roller rockers you can put then on in a few hours in the driveway. Once the car is running and it hasnt hurt your pocket too bad then go for it later on when you got the coin. Unless its the cheapest rocker for your cam. Aka its high rpm or high lift. Your appears to be both. For chevy you can buy cheap stamp steel rockers that are really strong. A nother bonus may be if the stock style rockers are 1.5 this will help with cam break in and initial tuning. Then the 1.6 rockers can go on once your get the car dailed in and it stops scaring you.
Sometimes the motor builds get expensive best to hold a few bucks in reserve. But i could be wrong im not up on the fords sep the 80/90's 302 since i had a few of them.