If that is all you plan to do the tear-down is not necessary. Everything that you say you want to do is pretty much cut-and-dry because the beauty of the small block Chevy engine is everything fits everything with just a few exceptions. All the valve cover gaskets are the same from 1957-1986. Same with the front and rear main seals. In late 86 there was a change from the 2 piece rear main seal to the 1 piece rear main seal. They will not interchange.
One way to determine a close proximity of the year is to look at the valve covers and the way they are bolted to the head. The 86-back will have four 1/4" bolts holding it down, 2 on bottom and 2 on top. The late 86-on will have 4 bolts going into the center of the valve cover with ridges on the cover from front to back.
One other change you might find, depending on the year, sometime in the mid 70s, the oil pan gasket was changed because the timing cover had a larger radius on the bottom. If the engine has an HEI distributor from the factory, it probably has the larger radius on the timing cover. If it has the conventional points type distributor than it will have the smaller pigtail going around the timing cover.
Since you have the block casting number of 3970010, it would have to have been one of the following engines.
3970010....302.....69....4 bolt main...Z-28 Camaro
3970010....327.....69....2 bolt main...Trucks and industrial
3970010....350...69-80...2 or 4 bolt main
All of these engines had the same 4" bore, used the same crankshaft bearings, rings, seals, gaskets, timing chains, connecting rods, flywheel, harmonic balancer, heads, intake, etc. The main difference is the 302 has a 3" stroke, the 327 has a 3.25" stroke and the 350 has a 3.48" stroke. Although the pistons are the same bore, they will not interchange without exchanging the crankshaft also because when the length of the stroke is changed, the location of the wrist pin in the piston also changes to keep the piston at the correct deck height.
If I had to guess, I would say it is a pretty good bet that you have the 350 but no way I can guarantee that.
AHAAAA! Found it! One of the numbers you listed ended in the suffex code TDK. Below is what I found.
TDK 1972 350 175 hp 4 bbl conv. cab, a/t
TDK 1980 350 155 hp 4 bbl van & bus,m/t
So, we know that your engine is a 350 and can be either a 1972 or 1980, more than likely a truck engine. The 72 will have the points style distributor and the 80 will have the HEI. Both are fully interchangable. This should give you all the information you need to do what ever you want.
