6.2 block conversion to 6.5 question

[6.5 Knuckle Buster]

Hey guys, haven't posted any questions in a long time, but there are a few senoir member here a really respect the opionion of. Last week I tore the heads off one of my trucks with 222,000 miles thinking the low compression with the results of head cracks and had plans of replacing the heads with new ones and replacing the pump and turbo with ones I picked up on a blown goodwrench with only 65,000 miles on it. Problems now was the truck,s motor number one cylinder that had ate a glow plug tip last winter had a scored cylinder wall now. There were no marks in the head or piston, but glow plug diet most have done it. Now deciding to replace the motor with a rebuilt long block, I have purchased a rebuilt long block from a rebuilder that uses older 6.2 blocks that are bored the .079 oversize to increase displacement to 6.5. The builder feels the older 6.2 block to be superior to the newer 6.5 or even the "New casting " 6.5. Their reason for using the 6.2 was better cast material and a history of 6.2 block inspection yeilding about 500% more usable non cracked blocks. My concerns were, no squirter in the older 6.2 block on back clylinders as the later model F series. Their theroy, you don't need the extra oil thorn onto the back cylinder if you add upgraded cooling sytem as was done on the F series motor and add a high volume oil pump. I am picking the motor up Monday. Does anyone have any input?

[trukdoc]

..."they" raised displacement did they drop compression ratio for turbo? do they know about your "mods" piston cooler nozzles were added to help with longevity and heat at piston crown how good is their warranty will they stand behind it how are your electronics are all your sensors and sensor attachment going to interchange with this engine...6.2 and 6.5 are same basic block but gm hasn't built 6.2s in a long time and you got a 98 just asking jd

[6.5 Knuckle Buster]

The deal is done, would I do it again, most likely not. I will go light on some of the information here until the results of my core charges are completely settled.
The builder starts with an inspected 6.2 block, most likely something picked up from old military surplus or something. Cylinders are bord about .075" oversize, then remaining .004-.005" are honed out on the Sunnen. Engine is assembled with new and improved cylinder heads with oversize water passages and improved cast iron. Engine is sold as a long block and all the externals from old motor are switched over. However, I am still concerned about the lack of oil nozzles on the back to cylinders that are missing on the 6.2. Their story, "they have added a High Vol oil pump and with the additional cooling mods made on the F motor, and a high Vol water pump will be no problem. I only hope they have adhered to the additional piston to cylinder clearance requirement on #7 and #8. I am putting my 1998s dual thermostat housing and a 130 gallon water pump on along with all the sensors and external from another low milage motor I have that is blown up. I will finish switching everything over today and drop in motor tomorrow. I just signed on to read some detail about injector pump timing and installation... Details to follow, thank for interest JD