Re: WOW ! I thought I was on my own...
Are there no hills where you live? No starter fluid? For all that, I'd buy another carb first, and get the upgrade.
If you finish welding that up with a 3rd roller and adjustment provisions, you'd have a might fine bicycle trainer. Maybe you can sell them as a side business.
1" roller Dax Friction Drive and Tanaka 3300 with mods.