A current floor plan and a planned floor plan will help you get advice. Typically a tub drain is not able to be used for a shower as it will not handle the amount of water produced by a shower.

Use

the plan is to use the same shower drain, just be off center.

You will need to move the drain if you want best performance and comfort. It is not a big deal to do. Also verify if that is the current required 2" drain, or the old 1 1/2" drain. If it's the 1 1/2" drain, that will have to be changed out anyway. You need a larger drain for a larger shower.

" You need a larger drain for a larger shower. "

Just curious why you would need a larger drain for a larger shower DeWayne, wouldn't it be the same volume of water regardless?

Larger showers are assumed to have multiple fixtures being installed. You have large showers needing to move up to a 3" drain, or 2 2" drains, depending on their size. It's all about DFU ratings. Also, that looks of an age to have the older 1 1/2" drain size, not the current code 2" one.

" Larger showers are assumed to have multiple fixtures being installed "

Well obviously more fixtures would mean more water but the OP never stated your "assumption", so it really is incorrect to assume that but then again...............................