Can a 1995 350 Chevy Lt1 Corvette engine swap into a 1972 Chevelle which originally had a 307ci without any modifications?  Please advise.  Thank you.  

No!

The 95 LT-1 is all electronically managed, the closest to electronics a 72 chevelle comes is the radio.

If you go with the fuel injection of the LT-1 all the electronics, sensors, computer, wire bundles, exhaust system, fuel system including tank and plumbing and exhaust have to come with it. The cooling system will have to change to support the reverse cooling that will include electric fans.

The LT-1 can be converted to a carburetor and the electronics done away with, but even that's fairly complex and expensive. It takes a specail intake from GMPP. This will allow the use of a carburetor and a distributor. The engine has to be opened up and the existing oil pump drive removed and a coupling installed to accept a conventional distributor that will also drive the oil pump. The front mounted Opti-Spark has to be removed and it's drive gear and shaft removed and the drive shaft hole plugged, GMPP also sells a kit to do this.

It will drop on the 72 engine mounts and will bolt to the old transmission what ever that may be. Don't expect the old TH350 or 400 to live long behind an LT-1. A three on the tree Saginaw won't last long either.

Bogie