Wondering what each of your specific reasons are? (I will be faced with the decision whether to tear the heart out of my 6, so wondering what some specific regrets are from those who have done it.)
He has an early A. The V8 means tight exhaust mainfolds or fenderwell headers. Steering clearance issues. etc. Everything is tight on the early car with a V8. Adding the 727 just makes it tighter. The early car was designed around a slant six.