Customs 51 Packard, drivetrain suggestions

You could always go the Macauley route -

 

Understand putting a 440 and A-518 into a Packard is the Combo I would not choose [I posted my recommendation earlier]

I have mixed opinions about adapters after a friend used this method to fit an A-518 behind a 383 in a 67 Coronet.
The kit available used a 1/4" thick adapter plate so it relied on countersunk cap screws and bellhousing bolts that held in with only 1/4" of thread .
These eventually stripped and needed studs TIG welding in place from behind.

The other issue was the spacer on the back of the crank that is needed to compensate for the adapter thickness. This needed grinding because of run out.

Eventually the whole adapter was an exercise in futility, and ditched in favor of a JW Bellhousing which is up to SFI specs
This bellhousing is $200 cheaper than the adapter kit and allowed the B starter to remain in stock position.
The only scary part was taking to the trans with a sawzall and grinder.

 

I hear ya. I am continually amazed by folks selling something like a trans adapter that is only 1/4" thick unless it is sandwiched and even then 1/4" isn't ideal for locating dowels.

 

My buddy, Al replaced the fried straight 8 in his '50 with a 460/C-6 ford combo. He likes it.

 

Some are only 1/4" thick aluminium. [my friends wasn't]

Here is a website selling them....
https://transmissioncenter.net/shop...ge-small-block-518-transmission-6-bolt-crank/

From their description [circled in red]



For $200 less [but a bit more time] this is the alternative


This ^^^ I would trust more. And it is SFI rated