[Denis]

decodes as early 69-73 small journal 2-barrel 327 block, consistent with the J-10-8 (12/10/8) casting date.

and now for something completely different:

for all you other blind 40-somethings out there, the latest issue of hemmings muscle machines mentions a new product which is safety glasses with built-in reading magnification at all the popular levels: 1.5, 2.0, 2.5, etc. cost is 15.00/pr -- i called and ordered a coupl'a pair (need the second pair to find the first). will be indispensable in the shop. available from usa weld 1-800-USA-WELD.