The cylinder kits they sell on e-bay are garbage. Get a used OEM cylinder and have it re-worked. The price they sell them for looks very appealing but in the long run, you'll be spending money all over again to make things right.
Nothing to get nervous about. Just make sure that when you purchase one on ebay, it has no stripped threads, broken off studs, busted off fins, as low on the over size you can get, and a bore that's relatively not too f*cked up like a ring that has snagged a port. I've purchased many cylinders off ebay that were great prices and in great condition. If you look, you will see that the prices have dropped on used OEM blaster cylinders on ebay. Thats because all the ignorant, lazy and cheap "chunk heads" are jumping on those "inexpensive chinese top end kits.
Do yourself a favor and get a used cylinder in good shape and send it to Ken at ... http://www.kenoconnorracing.com/
When and if you do purchase another cylinder off ebay, you will notice that most sellers that are actual shops, offer a quality used cylinder with a money back guarantee, so there is.nothing to worry about. Always read the description and ask the seller questions! Hope this helps.
One other thing... Get your head "re-chambered" into a high compression "Hemi head" and get even more power all while running pump gas. Port that sucker too and you'll double the output
(around 30+HP) with the reliability of a stock engine ( around 16hp).