Welcome Mr. Pirate-
Expensive versus savings, it all evens out.
Some of the frame mount guys are keeping a running tab, and I'm hearing $450-500 before they are running right.
Hopefully we can help you "not waste any money" before you get rolling, and that should save you some bucks, there are plenty of stories (mine included) where I wasted money or broke down.
Kits are in the $550+ range, and maybe you could save a hundred bucks if you get the mount/kit, and buy an engine that matches the clutch pattern.
(But then you'd have to have calipers)....Yada yada, shelves of wasted money. I have 5 extra gel saddles gathering dust.
Don't skrimp on the saddle, I've seen texasroads, and you are going to a "speed enthusiast" I can tell that from the intro...
I have a twenty dollar torque wrench, used once, busted made in China junk.
So, we got your bike scoped, 12 gauge rear spokes start at $30-40. Highly highly advised.
And if nothing else, you want that rear especially "flatproofed", since all the action is back there, the back tire tread wears twice as fast as the front.
No flats on the rear, that's the name of the game.
You have an existing bike, all your attention is on the rear, zip ties and fix the brakes on the front is all the work necessary (until you are ready for loooooong distance ).
To run either belt or chain, ya need the back wheel "solid".
We get everything aligned, lock the threads, crank it an GO....
No more "cost" except for fuel mix.
Do it right and you will be smiling thousands of miles down the road, without is "costing" you anything but gas/oil.
$650 bucks and "you're in"...about the same as a used "horse", without the hay.
That sound about right gang?