I have done over a dozen cars that i evacuated the r12 and recharged with r134 and had zero issues with all the cars , i guess in theory it all the concerns are true , but i think the newer systems are more problematic,
That is way to close , you gotta have at least an inch if not more of front to back and side to side play in the natural operation of your engine , especially if its a 4 speed and stock motor mounts.