I currently pull a Case DC with 4" pistons in 4500 and 5500 pound classes. I'm placing and winning occasionally but would like more power for next year. I wanted to know if someone might have some good used 4.25 or 4 3/8" pistons they might want to part with. If not does the John Deere 3020 gas pistons work well and will it require much work. Do they get to the top of the block with these pistons? I also would like to know if my 5505 head will perform good enough with this setup. Finally, do I need to concern myself with the rear main bearing support as others have mentioned with this setup and just what does that involve? Thanks!