I read somewhere that you could interchange many or all components between 6.2 and 6.5.How much of this is true?Can I use a 6.2 bottom end with 6.5 heads and turbo,electronic pump?

Most parts are interchangable but not exactly the same. 6.5 heads have the injector holes machined at a different angle than the 6.2. This requires modifying the injector lines or using a replacement line set that was made for retrofitting new engines to older 6.2's. I believe that 6.5 heads on a 6.2 decreases the compression some what, because the precups have a larger opening in them than the 6.2 precups. I am currently running a set of 6.5 heads on my daughters 86 6.2 blazer and I think the lowered compression makes for a little harder starting when cold. Probably better however for a turbo. Rods are the same as are cams and rockers and bearings. Cranks are different in that all 6.5's have a one piece rear main seal and the only 6.2's that share this are the ones that were made from under bored 6.5 blocks. Even a 6.2 injection pump will work on a 6.5! Been there done that. 6.5's use short injectors to clear the turbo, 6.2's use long injectors except on the vans, they used short injectors.

Are the pistons on 6.2's ceramic coated?

If you want to use the 6.5 electronic pump, you will have to use the timing cover from the 6.5 as well as the timing set. Pretty sure it will work.

You'd have to use a 6.5 'tronic pump drive gear too.

You will also need the 6.5 balancer since the snout is a different length needed to work with the 6.5 timing set. 6.2 pistons are also anodized like the 6.5's, but the crown is not as thick making them more prone to cracking if high boost levels and high egt's are run.

Thanks for the all the info!!Don't you just love the interchangability of G.M!