If it was me, I'd go mustang.
If you were looking for a V8 for cheap, the F-body would be the way to go.
The interiors on most of the V6 model F-bodies are even cheaper than a V6 mustang
interior. Not to mention, the 3800 series from chevy always felt slower on the top end than the ford 3.8.
But, you asked on a mustang site, go for a mustang. Secretly you want to.