Taimar unleaded converstion

[dcz3580]

My 1977 Taimar (Essex 3l V6) is stilling running on the lead replacement petrol which is becoming harder to find and is restricting where I take the car (just incase I can't find any for the jurney home). I've heard about pellets being put into petrol tanks which then allow the use of unleaded petrol. Are these pellets any good, or should I only consider a proper converstion?