So.. in the natural order of things around our yard.. we ended up throwing the 258 in. However we ran across some problems.
We took the 6 cyl crossmember out of my 77 hornet (its getting the whole drivetrain from a 74 hornet) and used it in the 79 spirit GT.
I left the original 79 spirit 304 front sway bar, but when I placed the 258 in and tightened up the sway bar link pins, I noticed the oil pan was about 1/16 th above the sway bar, hardly any clearance.
I must be missing an interchange somewhere. is the sway bar different for a 304 vs 258?
I'm sure I need more clearance between the pan and the bar.
I haven't done it yet, but my next thought was to swap out sway bars and put the 77 hornet 258 sway bar in and see what it looks like.
Thanks in advance for any input, or advice.