Not sure what kind of budget you put on getting some brackets but I'll give you 2 ideas and see what you can do from there.
Optioin 1. buy them already made from
http://www.cipherauto.com/Planted-Seat- ... AT-BRACKETOr option 2. I've made some like this before and it worked great.
it involves 12 feet of angle iron and 16 bolts and nuts.
I used thick perforated angle iron. Not the flimsy stuff.
It takes 2 6 foot pieces. Cut one into 18 inch sections. This is for the floor.
The other cut into 4 16 inch sections. These are for the seat.
Before cutting, measure the pre-pierced holes on the angle iron. Make sure they line up with the seat. In total the had 1-2 centimeter gaps between each 16 inch piece. Make a jig to make it easier to measure the holes. Once you have 4 cut. Mount them facing in on the bottom of the seat.
On the 18 inch pieces. You shouldn't have much to worry about. Once they are cut to 18 inches, drill out the front and rear most holes a tad larger to fit the stock bracket floor bolts.
Once done, line up the rear most holes on the brackets. Place a bolt through and tighten it down. Toss a bolt in the front most hole on the 16 inch piece.
Now you should be done. Bolt them in and have fun.
For the seat belts, use your imagination. I am going to make custom brackets for the buckle.
The image attached shows you how it should be done.
