Should I make the swap to G3?

What will the g3 do that your 408 won’t? That’s the big question. If you’re happy with the performance of the car now then I can’t imagine the work will be worth it. If you need a bunch more power or are looking to lighten up the car, or make more useable power than the current small block can handle then it’s a no brainer. The g3 imo is worth it if you want 600+ hp capability, fuel mileage, and weight reduction. Just my thoughts.