Backfiring CJ7

I have an 82 CJ7 with the 258 six that will hardly run and backfires when the weather is cool (less the 50 deg) until it warms up. I have rebuilt the carb and removed the vacuum lines and plugged the leaks but with no great success. I have also replaced plugs, dist cap and wires. The choke appears to be working OK. Is a new carb the best alternative at this point?

Backfiring often involves the timing.

'94 YJ almost all stock, '85 CJ7 almost nothing stock.