383 power upgrade help

Okay I'll need to pick one of those up before I buy any heads I want to do this right the first time but doesn't always go that way
See if you can borrow one or have a friend over to check it before purchasing one for just this alone.
I don't think I'll ever be taking it to the drag strip or maybe once mostly looking for a nice powerful street car I don't have any gearing ratio in mind but I'll be on the freeway pretty often now that I think of it. Yeah I need to fix the linkage on the OD it's not set properly but I have time for that
Is your trans an automatic or manual. I thought I read manual before?

Freeway traveling? At what speed?