I would say you will be safe with the 4 bolt block, but upgrading to studs will make it much stronger. Just make sure you have the line bore checked if you do go with studs. The extra clamping force the studs provide sometimes distort the bearing bores so get it line honed to be on the safe side. Make sure you check your rod to pan rail clearances. Sometimes they clear sometimes they dont. I'm building a similar bbc 496 except I am going with more compression ( 13 to 1) and a big lunati solid roller and mine is a 2 bolt but I have studs and a stud guirdle, what I did was after I got my block bored I installed 2 pistons at a time on the crank throws and rotated it alway around and checked clearances and then you can take you block back and have it vatted if you had to do any grinding and then have your cam bearings installed.
Goodluck and welcome to the forum, Charles