I have personally installed the MP .474/280 cam in an otherwise complete stock 318 and I had no issues. I later upgraded my valve springs to match the cam. No, this is not a recommendation, it is an answer to the question by the OP's 1st post.
I assume you had some non stock converter.
In my stock 1972 340 Challenger with Stock J Heads it needed a small one. Used a, Street Fairbanks one. What they markered as a modified Hemi. Was a,step above the neutral balanced 340/440 one's every one looks for as,Dayco rebuilt 340 converter.
The 274 MP cam needed a little more than my stock 340 one to run well. With 323 gears