FWIW... I certainly DO NOT claim to be a know-it-all of the 65 GS by any means, however, I removed a 401 from a 65 GS vert TRANS AND EXHAUST MANIFOLDS INTACT... FRONT CLIP REMOVED is the easiest less obstructive process... SET the car up on 'jack stands' as high as you can.... plus utilizing my "ENGINE LEVELER" is always a huge help as Joe mentioned. Remember to remove the GROUND STRAP on the back of the PASSENGER SIDE HEAD to firewall!!
Removing the engine/tranny assembly was maybe a lil trickey especially driver side manifold at the cross member. Prying a bit here'n there using shim of 1x4 lumber to help guide it out...
When I RE installed the 401 back in, I did it complete with manifolds, trans, starter etc intact... no real issues using the same 'pry bar, or 1x4' to help it along...
Worked for me.
Wheelz, Tampa Bay