If you arent having any problems with your engine running on hi test pump gas, I wouldnt mess with mixing them. If you are just wanting to get rid of the racing fuel, it probably wouldnt hurt to dump in a gallon or two with each fill up. Running the higher octane fuel, if your engine isnt needing it, can and will hurt your performance. You dont want to run any more octane than your engine actually needs.
The best alternative is to just hang on to it to when its 4 days til payday and you have an empty gas tank.
As for lead substitutes, unless you have a problem with exhaust valve erosion, I wouldnt bother with the stuff. I have run pre unleaded gas engines for several years on unleaded gas and didnt have any problems of that nature. And if you do have a problem with exhaust valve seat erosion, the best thing to do is to take the heads and have hardened valve seat inserts installed.
A word of advice, if you mess with toluene, do it in a well ventilated place, and wear protection on your hands and a real filter mask. Highly toxic stuff.
I used to run a 50/50 mix of 105 AV gas with 91 octane pump gas in a modified I raced. Decided to run it on just the 91 octane once to see what happened. Actually ran better. I was running a 10.5:1 compression ratio in a Cleveland.