Engine at the back 330817.

At the front 14B459345 / TI030CTA

Head GM7T / J4 73 / 333882

Whatever that means.

I hope that I can use them with unleaded Gas

Block:
330817 SB400 72-80 2bolt mains.

Heads:
333882 74-80 350/400 75cc chambers 1.94 / 1.50 valves, should have the hardened seats already, unleaded should be no problem.

These heads will work well for a street motor, but are not so good to have port work done. (I use the same casting number).

Taking the two numbers and the date ranges indicate this motor should be at least a 74. Heads were cast in 73, the whole motor was probably in a station wagon, light truck or full size car.

But you gave more info that confirms it.
The CTO suffix code, (the last 3 in the front block numbers). show this motor was:

Built in 1974
Suffix code of CTA
SB 400
Automatic transmission
Vin code U
Engine name LT4
HP 175
2 Bolt mains
Bodies used in "A" "B"

Cheers,
Andy