Ethanol is corrosive and can have adverse effects on rubber components, esp. older rubber. Keep an eye on the bottom of your carburetors and other quasi-rubber components. If your carb diaphragms are more than 10 years old you might buy some carb rebuild kits to keep on hand.
I live in California, which has had many concoctions put in its gas. I put a new gas tank in my BJ8 a long time ago--10 years, maybe more--and sloshed it with Hirsh's tank sealant. My carb jets and diaphragms were replaced quite a while ago, and I've had no fuel system problems whatsoever (well, except for the occasional finicky fuel pump). I think the newer, alcohol-resistant rubber carburetor components are colored, usually green or blue, but I'm not positive.
100LL avgas still has a lot of lead in it, 2g/gal of TEL I believe (as opposed to 3g/gal in the older formulation). Treat is as the toxic chemical it is, but mixed with pump gas your Healey should run just fine on it (however, I believe it has a lower Reid Vapor Pressure than autogas and it might make the car harder to start when cold). Last I checked it's $4-5/gal. Some FBOs won't pump it into cars or cans, because it's exempt from road taxes and the revenuers could get them.
Aside from the above, your car should be OK on pump gas, lowest octane that keeps the engine from pinging. I always run 'high test' on principle.