Moving tub drain and tying into toliet drain

I am moving my tub drain to middle of where tub used to be for a shower drain. See pictures. What is the best way to tie the new shower drain into the main drain? Should I cut two new holes in joists and tee into the toilet drain, then can I use the previous tub PVC for the vent. Or should I change the tub PVC to 2" and use existing holes. My worry is if using the existing holes is that I will have need to use a 90 degree turn where the tub drain used to be to tie in and I will have too many turns.

Also with this previous setup the toilet seemed to plug up regularly should I cut that offset out and make it straight or could it be the wet venting off the toilet drain? Should I redesign the vent for the shower so it is not wet vented?

The best way would be to use the same route as before, install a vent in the wall and come back to it.
You can bump the pipe size to 2" whil you are at it.
The vent can tie back in at 42" from the floor.

You can't bring the shower downstream to the toilet without venting the trap first.

Agreeing with Terry- the shower must have a vent rising vertically off it's branch prior to it's connection to the primary line.

Without measuring, are you sure you have enough room to extend the line with the required slope, and still have enough room for the p-trap and drain?

You might want to check the code on where in the joist you can cut holes...get too close to the edges or ends, and the joist loses a lot of strength. Double-check the slope of your line to the toilet...it also must have the proper slope with no dips, humps, or flat spots. Those are probably the biggest reasons in a house for clogs.

Why are you moving the drain to the center of the shower.

Why not use a linear drain across the back side.

The drains from ACO work with any approved shower waterproofing system!

Thanks for the feedback guys. I like the linear drain idea after looking at designs online. Thanks.