i have a 70 ke 20 and it has a 3k with a blown head gaskit, i have a 3k with burnt rings and a 4k of unknown condition(fine apparently) I'm wondering what i should put in or if i should just fix the 3k. i have an idea of what i have to do to change the motor and a couple of mates who know what there doing. i just need to know if i need to change parts on the 4k to put it in and if that would be to costly, ill soon have mounts. or should i just change the gaskit and get the head machined on the 3k. or change the gaskit and then swap heads with the other 3k. I'm pretty confused ive got 1200 to get it going strong any ideas? much appreciation, woody