sohc pistons in a twin cam is actually great for a na ka(obviously)you can buy oem sohc pistons from nissan for about 160-180bucks, with rings and everything,with the 89 pistons it'll put you between 11:4.1-11:6.1 compression.and I think you have to use single cam rods also,it would def be a nasty na ka,with a fresh build,single cam pistons,header,maybe a little head work,go for it.