Which engine?

Budget hasn't really been set yet.
Horsepower is what ever it ends up as I plan on this being a street car for my pleasure and I like the feeling of the hard acceleration from time to time. You know planting someone back in the seat hard and seeing the whites of their eyes from the surprise.
The engine I currently have and planned on using is an LA motor out of a 79-300 I scrapped as the body was too badly rusted to save.
I have seen some new Hemi's for sale with a 6 sp under 8k that include the computer, pedals and generally are ready to drop in a properly prepared car. They don't have any HP advantage over a good SB LA motor but it is a Hemi.
Problem is how much fabrication would be needed to drop the Hemi in. Is it really that $$$? Have many successfully done this in an A-Body? I've seen some in B-Bodies but none in the A.
I do have a BB k-frame in it right now but like the quick revs of the SB.
My real goal is to have a good looking car that will run well and be reliable enough to take a CC trip in it. I originally wanted something that looked original. But as you all know sometimes in mid build you tend to question what you really want and some times switch directions.