taking the sawzall or cutoff wheel grinder is the first step.
don't forget to slot or drill one hole a couple of drill sizes bigger.
this will help a lot with sealing, as well as cracking that sometimes occurs at the head flange.
i "stole" these ideas off of member Mr. Pbody many, many [and more manys] years ago, and these ideas will seal even the thinnest of flanges and prevent cracking.
Thanks Mr. P !

About ready for the run stand.

You could send it to me, I'd dyno it, then put it in my Dart and run it. I could send you a report from time to time to keep you in the loop. It would save you a lot of work.

Brilliant!!! Be right back, building a crate right now.