Daily driver small block build

I don't think the 5.2 would even need thin head gaskets. Remember, the Magnum engines have a shorter deck height, so they have higher compression already. IMO, if he finds a good low mileage 5.2 (they are still out there) all he needs do is put a chinesium Air Gap, a 650 DP, a good distributor with a hot advance curve and a set of long tube headers and he's so close to 300HP he'd never feel the difference.
i always forget that the 5.2 has a hair more compression.

the yards out here are absolutely rife with 5.2 and 5.9's so it's easy pickins. if you could snag a low mileage piece that just needed rings and bearings that'd haul the budget way in. worst case reman short blocks are like 8~9 hundy with a warranty.

with the right combo of parts, some judicious shopping and a little work, i don't think knocking on 400/400 wouldn't be out of the question.