65 A Code Engine Questions (restore to orig)

I have a 65 A Code Fastback, that I believe is a GT. (Past all tests I could find.) It has a 4th of April, 1965 build date.

The trouble is, the engine is a 66. I want to go back to orignial (or at least as close as I can). (Shouldn't have trusted, the seller's the engine could have been repainted, when I saw it was blue. But the car is for my dad and he liked it.)

The 66 block, I believe is a 6 bolt block, whereas the 65 could be either a 5 bolt or a 6 bolt? Does anyone know what month this changed? The current bellhousing doesn't look 40 years old, so I am guessing a Feb-April 65 289 would be a 5 bolt block? (I am trying to decide if looking for another 289 block in better shape would be easy or not and if it would work with the current parts.)

Can anyone suggest a good book for rebuilding an engine back to 65 A code specs? (I believe the A code has higher compression/larger pistons and a more agressive cam and a 4blr?)

Also, this car isn't likely to be sold anytime soon, so I am looking for the do it right over do it cheap in the engine rebuilding category. So, any suggestions for engine life would be great too.

Thanks.

Thanks for the replies.

I was emailing a guy several days ago on an engine he claimed was a March 65 block. He didn't want to send pictures (red flag on that). I dropped it when he said the block was a 5 bolt block.

As for the suggested book, is this it this? http://www.amazon.com/How-Rebuild-S...7011252?ie=UTF8&s=books&qid=1180317008&sr=1-4 (It is by Tom Monroe.) It does have a negative response on value trains and seems a bit dated at 1987 (but not much changed on these engines in 40 years).

P.S. took the car out with my dad today and did some less than responsible driving. It was fun. I also have a feeling the synchro for 2 gear is going, but the trans was going to need a rebuild anyway.