60s /6 to 727 adapter

This last Friday I picked up a complete 225 and 727 supposedly pulled out of a 64 pickup.
The whole reason I got this is for the adapter plate they used to use on /6-727 applications before they came out with the/6 specific 727 case, as I also have an A500 from a Dakota sitting here. That adapter plate is tough to get these days.
I have a while and I'm not sure which way I'm going on this build but it gives me another option (besides adding to my confusion on which way to go)
This is for my 85 d150.
Ok now down to the meat and potatoes...
I have heard about having to grind "something" about the starter hole to make this combo work// as this was also at the beginning of LA series engine production and that the trans actually has the "poly" 318 Bell housing which is supposed to bolt up to an LA but is somehow slightly different than the poly.
This adapter puts the starter down low where it would be on a small block instead of high and tight like a typical/6.
What has to be " ground out" to work with the actual "LA" series engine trans bolt pattern?
Whether I use this combo or whether I instead put the 833OD in and row my own gears, I have other questions to work out (such as whether a 3.21 will be too high to take an OD gear with 235/75/15s) since those same size tires and 3.07s were too much for the 4.0 inline the was in my wrangler below about 60 unless on dead flat ground or downhill but I'll consider those things later.......