Flathead 6 "G" model motor mount replacement

[Vintage Copper 47]

So I need advice.. I just got two NOS six cylinder motor mounts from Fred at Southside Obsolete. Fred messaged me to tell me that the repair manuals DO NOT show the standard V8 donuts and bolts underneath the mount where it attaches to the frame rails. Well, I checked today, and there IS indeed rubber donuts with the bolts attaching the mounts to the frame rails.. Could whoever had this car before put them in as an extra cushioning measure? Also, I looks that if I install the new mounts without these donuts, the motor may be lowered by a half inch and it looks like the exhaust pipe will then hit the forward crossmember... Just wondering what I should do before I start wrenching..
One last thing, would it be ok to use a block of wood alongside the oil pan to lift the motor to remove the mounts or should I use a chain with hangers to a coupe of headbolts? Any tips would be nice... I've changed motor mounts in newer cars.. but never a flathead...