Mileage wise. Really not worth it. You might see 2-3mpg gains.
Drive ability wise TBI is worth the headache and $500 for the harness and standalone ecm.
But, you really should be starting with a 87 to 95 truck engine if you want tbi.
No headaches with the different angle on the intake or guessing what cam gear to use with the tbi distributor or issues with the cam/valves working with the factory tbi.
Keep the thing carbureted or grab a tbi engine to start with.
Or email the company below.
affordable-fuel-injection.com
Below is a link to a Michigan based company that makes standalone TBI kits. They can also install tbi on almost anything having it working like factory. After a few emails.
TBI harness, chip, and ecm to run a factory TBI engine((you supply the fuel pump( use a 87 squarebody saddle tank)). $500
affordable-fuel-injection.com
Or you can take virtually any stock to mild SBC and they can give you everything you need to run it for around $1300.
affordable-fuel-injection.com
If you say have a more built engine like say a 383 or a 468 then we get into the heavily modified NA setups. In which your going to have a few emails and a build sheet would be nice. But they can make that run TBI also with replacement parts that you can find at any parts store.
affordable-fuel-injection.com