SteveG

The only important interchange issue, if you plan just a long block swap, is to make sure your replacement engine has pre-1987 (1970-1986) heads or replacement heads with this intake manifold bolt pattern AND drilled and tapped accessory attach holes in the ends of the heads. If you try to use earlier heads, TBI heads or Vortec heads, you will need to change the intake manifold and likely some of the accessory drive bracketry.

Look here: (StudeTech - Page 1)

Use this stuff... https://www.amazon.com/dp/B07X9X7JWP?ref_=ppx_hzsearch_conn_dt_b_fed_asin_title_1

A 1983 should already have electronic ignition. It should be a 305 LG4 with computer controlled HEI. If you are getting rid of the computer controls, then a stock GM HEI distributor with vacuum advance is plenty good for the stock 305.