Consider a MTB- plenty of them with 13" frames 26" standovers-and low prices.
A bike is a bike.
Granted rigid framed bikes aren't exactly MTBs - but they were sold as MTBs, so that is how folks usually advertise them.
Just put on slicks-call it a day.There is far better tire selection with 26" vs 650.
Or You can also get a hardtail(suspension fork) put a rigid fork on if you want..
The stuff about "you need a corrected fork" is BS.
Granted you will have a bit more weight on the front end with a slightly shorter fork- but so what??
Try a MTB.
Charlie