428 IMO. I believe Probe makes a 4.145 shelving piston for your application this would be only .015 over. You could contact Barry R of Survival Motorsports (Forum Member) for those. I would be looking at getting a dished set if you want to run pump gas and iron heads, if race gas only then get the flat tops. If your not going to get real crazy with the rpms or power level and it is gonna stay N/A, the stock rods will survive, I would just have them resized and new ARP bolts installed. I wouldn't run the stock rods much over 6000 rpm.
My definition of streetable is what most consider towards the wild side. I wouldn't bother with the roller cam if you want to keep the streetability and have a maintenance program that only happens by accident. Plus, without the roller cam you will be able to save money on valve springs, pushrods, lifters, and the cam itself will cost about 1/3 to 1/2 as much. Sounds like you already have a good rocker setup so I left that out of the recipe. Depending on what heads you actually have, I would suggest a cam in the mid or high 240's @ 0.050 duration on the intake and low 250's @ 0.050 on the exhaust, 110 LSA installed @ 106 ICL and around 0.600 lift. I would call Ken @ Oregon Cam grinders and he can get you a custom solid flat tappet cam ground for about half the price of what comp cams will do for you and he has raced FE's most of his life. This cam should defiantly have a rumpty, rumpty idle and pull real hard to 6000 rpm or so which IMO you don't have any business running a stock bottom end any higher than that unless you spend the money and get the block crossbolted and a set aftermarket rods. I also tend to error on the side of overkill because it just isn't worth it to me (and my checkbook) to push things to far and then the engine pukes its guts out and you have to start over.
Use the Intake you got, it will work great, Headers you got are good, I would ditch the Dual point for a Recurved stock Ford Duraspark and a MSD 6AL box personally, but you can obviously make the dizzy you got work. I would be looking for a Holley 950 HP or if you want to go old school get a tried and true 735 or 780 cfm holley that ford used on the CJ/GT cars back in the late 60's early 70's. I would also get a little looser converter or see if you can have the one you got loosened up some.This should get you started, and you will have to stock up on tires I guarantee you. Good luck and have fun.
1976 F-100 stepside
390/C6/9 inch
12.73 @ 104 mph
3900 lbs. of pump
gas burnin' pickup
