Are ARP head bolts really needed for a mild build?

I believe the problem is getting even torque on each bolt--and it holding that spec longterm. Your taking a chance of having a blown head gasket with the 40 year old bolts.

I did re-use the main bolts on my 340 since the bearings were still 1972's. Rods got new bolts and head bolts were changed back when APR price was only $50 a set and were used once.

Your pushing the compression for pump fuel, any pinging isn't going to help. Only time I blew a head gasket was on the freeway going all out--then you see lots of white smoke and the car slows down. I still was able to get the car back home, smoke and all

Edit..oh you could damage the block threads, least take a good look at all the threads on each head bolt, if all good-no nicks, then you MIGHT get away with it but for how many months or years ?