question been searching around for a couple hours, when mounting the sub marine belt with a 5 point only way to get it in is to weld in an eyebolt below the seat? trying to avoid that but im not seeing an alternative

 

Welding in a mount is probably the best way to do it. The problem in any car is finding a secure mount that you can bolt to. The stock Z floorpan doesn't really offer any other options.

 

Actually you weld in a place, and bolt the eyebolt thru the plate

 

I'm not sure you need to weld an i-bolt in or the plate. Most Race Organization will allow for a very LARGE Fender Washer on the the bottom of the floorboard with a hole drilled thru for the i-bolt. (but you want more than the minimum)

In my TT car I used a 6"x6" pretty thick (maybe 3/8")steel plate bent to the couture of the floorboard on the bottom...drilled the holes in the floorboard, and then had a smaller piece on top, then ran the Ibolt thru and had nuts/washers on top and bottom to sandwich the plates to the floorpan..

Note: I used 6 point belts, so just double what I described above

The bigger and stronger the mount the better.