Agreed The stock swap is straight forward, you could remove the trunion from the stock by removing the two pins, but it would be easier simply to purchase a $15 rear trunion for a fixed stock. This is the easy part.
Changing the frong handguard means replacing the handguard retainer, which means pulling the Front sight base and gas block and even then I'm not sure what would be required to replace the retainer as I haven't measured my tantal barrel to see if the retainer would simply slide on, and what grove is there or missing. In addition you would then need a gastube with retainers and I don't know if the tantal has the same lenght as a standard gas tube and if it will fit in the front sight base. Just sell the thing to somebody who wants a tantal and buy a 74.