198 numbers matching or 340 clone...... opinions?

This is really a personal choice, you need to decide what it is you want. Think about the pros and cons of each decision. I am not a "stock" or restoration guy so to me I would probably either sell it to someone who appreciates it for what it is or convert it to a V8. That said, they are only stock once and if you are not a hot rodder or HP junkie and just enjoy the car, then perhaps keeping it stock (rebuilt) is the best decision. Definitely going to be less issues and cheaper to keep it the way it is.

Perhaps another prospective, if you go to a car show and look at the A body line, you will find lots of 340 cars (and BB cars) but not a lot of /6 3 on the tree cars.