It is difficult to have it all at an even keel when the cars are so different. Maybe there's a price to pay for having everyone run whatever vintage car they please.
The F1s are as quick as the 13.5T TCs round the track. They are as quick because they get through the infield faster, not because they accelerate as hard or get to similar top speeds as the super powerful TCs. If we want an even field it would mean either slowing down the F1s, or speeding up the tourers to be as quick as 13.5T TCs.
Which then begs the obvious question, why not run the TC clubmans as 13.5T TCs if they are basically the same.
Secondly, is it fair to slow down the F1s when they really aren't all that fast down the straights? You could ban foams, which would slow things down. But the F1s look like lightweight twitchy things, I'm not sure they would be much fun on rubber tyres. I guess you guys who drive F1s can answer that
Lastly, I don't think it is good to equalize the overall lap times by making some cars way quicker down the straight than others. I'm no expert but I think that's probably conducive to high speed accidents which is ultimately what breaks cars.
A long post to basically say that I'm all for trying to make things as equal as possible whilst always keeping in mind that some differences between different classes are not easy to overcome... And perhaps cannot be overcome without doing something that actually spoils the fun.