Dany's Magnum swap starter engagement issues

So Danys Magnum swap into our '66 Cuda is almost done.
Only thing missing is a heater hose nipple that the local parts place will have in the morning.
So we decide to start it up with no coolant for a second and see what it sounds like.
Horrible grinding, no engine turning!!!
I mean like a Chevy with the nose broke off the starter!!
A little background:
'66 Barracuda originally a 273/904.
Engine and trans original to the car and in working order
Magnum installation went without surprises as we read literally every word on here first.
Except...
When we bought the engine i told them i needed the flex plate and starter off the donor vehicle.
A 2000 Durango.
When we went to put the Durango starter on it would not fit as it is hitting a projection on the block that is not there on the 273.
Not to be delayed we put the original starter back on. And it fit.
Now with the original Trans/converter/starter the starter does not have enough "throw" to engage the ring gear on the torque converter!!
I can only think the Magnum flex plate has moved the converter back just a bit??
I mean this bellhousing and starter and converter are all original to the car and the only thing different is the flex plate, right??
As to the Mini starter not fitting it was not with the engine when we picked it up and came off a shelf in the office when I asked about it, so not "really" sure it is correct.
I'm going to take it to the parts place with me in the AM and have them pull one for comparison to make sure it's the right application.

So, Our questions are:

If the mini starter is correct is it hitting the block because an early A starter is closer to the crank centerline? I know all about the early VS late converters, but do they have different diameter ring gears?

Does the Mini starter have more "throw" so it will reach the converter in its new position if we grind the offending bump off the block? Not looking forward to that now that the motor and Doug's headers are already installed!!

We are using the original Magnum Flexplate as it has the weights on it.
Any alternatives to this?

I cannot believe after all this the motor is probably coming back out...
HELP!!
Problem solved!!!!
Bendix drive of the original starter hitting the tone ring of the Magnum flex plate.
Mini starter hitting a projection on the Magnum block.
Die grindered it off and the Mini starter fits!!
An early A trans must have the starter closer to the centerline of the block than later transmissions...

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