That’s not true. At no point did EVH tell Peavey he wanted his signature amp based on a Soldano, nor was it based on a Soldano.
The 5150 was supposed to be based on a Marshall that Jose modded that EVH was going to provide, but the amp never showed up. He was looking for a company to put that amp into production at an affordable price. Signed a deal with Peavey, and they waited months for the amp to show up, but it never did.
Peavey finally had to get going after months of waiting, so they started the build based on the Peavey VTM (which EVH had tried and liked, which was oddly enough itself based on a Jose Marshall), added the Resonance/Presence features from their line of power amps, etc. Hartley (Peavey) suggested they try to make some tweaks based on amps they knew had at the time, and that’s where they tried to incorporate bits from the SLO, Marshall Super Leads, etc. But the platform was a Peavey VTM with some features from their power amp line.
Not sure where the internet rumors came from originally that he wanted some company to make him an SLO style amp, but it’s false.