You can do it, but it will drop your compression ratio by the amount of shelf that is created, which is also a shelf for carbon to deposit and create hot spots with or other problems associated with swirl, squish or whatever head and piston designs are built into this motor. People that have tried it, report no issues, but how long were the motors used for, and were they experiencing problems and not realizing it, no one can really pinpoint with scientific data to back it up.
Best idea is the use the proper sized gasket and some good ARP style studs. The factory gasket with proper mating surfaces (ie flat) is a great way to go on lower boost applications < 25 psi (my theory, not from experience). The only problem is that the 4g61t has no MLS gasket, although it would be identical in construction, with a different bore sizing.
I preach using the proper part for the job, on principle, knowing that people can use the other incorrect but functional part, is the other way to go, but at the users discretion.
