Classic/Antique Car Repair: Carburetor Problems in 72 Land Crusier, fuel injection system, vent hose

Question
I purchase a 72 Land Cruiser about a month ago and have always noticed that it had a strong smell of gas.  I just put in a new tank of gas and it is backfiring, hesitating and doesn't seem to have the top end power.  What should be my first step in trying to diagnosis this problem?  Can you convert a FJ40 straight 6 from a carburetor to a fuel injection system?

Answer
My first thought is bad gas. Your may try adding an additive to clear up that tank. The smell is probably a bad cap or vent hose problem. Shops that do inspections in Texas have a fume "sniffer" and can locate the leak.

Conversion would be very difficult and expensive. But with enough money, you can do anything.