So the most you want to take either stock block bore wise is 40 over . The cyl walls become to thin after that and you run into over heat issues and possible cracking in the walls .
A stock 302 block is a time bomb after 550 whp . Depending on the tune up some guys make more etc but it isn’t some concrete number . Concenus is they start to rattle the crank esp If you have any detonation or spinning the engine some high rpm and crack right up through the cam journal .
So if you are starting from scratch what’s the long term goal power goal ? If the plan is a fully freshened engine the 351 is a no brainer . If you’re just looking for a heads cam intake car that’s a 300 hp cruiser with the intent to never really turn it up to its limit then a 302 maybe out of explorer or something with good heads on it and a good cam would be easier on the pocket .
351 for power ? Let’s just say we have a stock 79 block and crank , je piston 30 over , good rods and a 78 mm turbo that’s been 8.52 at 157 in the 1/4 and together for 8 years .
Starting from scratch on the 351 youd need an oil pan , dist , matching upper and lower intake , headers , and 28 oz flywheel before even touching the motor . Also hood clearance . Can’t remember as I’m writing if you have a Stock hood or not but Guys Have used vert mounts and k member spacers and it has beem done under one .
You cannot plan the engine build until you decide your final goal power wise .
After you did that then you need to sit and make sure the chassis , suspension and every part In the drivetrain will not be a weak link . Building cars is fun isn’t it ?
I just realized you said you shouldn't bore a stock block more than .40 over. So does that mean I wouldnt be able to do a 347 from my stock block? Should I make it a 306?