I was in the same situation. Get 1/2” black iron and use about 8” of it. Buy rocker arm from rock auto part # MR-720 ( they are cheap). Get 3/8 black iron need about 2 1/2” long. Weld the 3/8 black iron to pushrod side of rocker arm. Drill 2 holes in 1/2” black iron to bolt to where your rocker shaft bolts to. Sand the 1/2” iron and the rocker arm till arm will move freely on 1/2” iron. Slide rocker arm on 1/2” black iron which is bolted to head. Stick 3/8 extension into 3/8 iron that’s welded to rocker arm. Forgot to add: you need to grind a horseshoe in valve side of rocker arm. I would post pics but don’t have a clue how to. With this setup, it worked great when I did mine and it’s on the cheap.