I have a old Dayton Shop heater, the nameplate on the back says peerless though model number UH 200. I need to replace the Magnetic gas Valve and the size is 3/4, pressure is 8oz, 50-60 cycles and 115 volt and model number VA435A5CG5X1, would like to find an exact replacement or at least something that would work.

You can try this

https://customer.honeywell.com/en-US/contactus/Pages/default.aspx

And ask about a replacement, or find a local parts store near you to cross reference your part. Like a Grainger's,

https://www.grainger.com/search?searchQuery=Honeywell+magnetic+gas+valve+VA 435A5CG5X1&optOut=0&NLSCM=4

Check eBay, there are some on there. Here is one.
https://www.ebay.com/itm/NEW-NO-BOX-HONEYWELL-MAGNETIC-GAS-VALVE-V8046C-1030/254016028986?epid=1400651902&hash=item3b2489013a:g:chsAAOSw6~pcCnLO:rk:4:pf:0