I still fix 6 cylinders like I have been doing for over 50 years. If I pull the pistons out of a GMC and the bearings still mike within specs, I tape up the rod journals and hone and crosshatch the cylinders. Quite often the original complaint was blue smoke and all it was is that the rings stuck since it was last driven. If I find aftermarket bearings that are worn beyond specs, I figure it is time for an out of frame. On a 6,I check the deck and if it is straight, I assume the line bore to be ok. If the block needs cylinders bored, I take that to a machine shop because I'm not equipped to do that. I pull the valves out. If they aren't burned and the stems mike good I reuse them. I narrow the seats a little with a 15° stone and a 45° stone. If the guides are bell mouthed, I press in new ones and ream them out to a little more than the minimum clearance. I have too many old jalopies to take all the blocks to a machine shop.
