The the thing that would be important to do is to make sure all the bat droppings are taken care of. Cause they do not smell good at. They're very potent almost like it stings the nostrils when smelling it.
I'm a hardcore Eddie Brock / Venom fan , but I'm actually not bummed out by this at all. So I don't mind Flash taking up the Venom suit.
Now I didn't know Flash lost his legs. Last time I was reading Spidey where Flash was in the comics was when Spidey was a teacher and Flash was in a chair with both his legs and he looked like he was a mush from being brain damaged.
If he does join I can honestly say he could play Black Mask. I mean he did play Cobra Commander and actually did a great job. So I can see him playing Roman and on top of that Black Mask originally was the main baddie for Batman Begins. But was taken out cause he wasn't that well known yet at the time or wasn't that big of villian in the comics like he is now.