If your doing it yourself, the price range is do-able. either way!
But if you want a shop to do the swap\upgrade it will cot you $1k just to R&R the motor.
I would find me the motor, complete with everything. I would probably purchase one from
http://67-72chevytrucks.com/vboard/s...d.php?t=614503
these would be complete and ready to drop in, all you would need is fuel delivery, mounts, cooling and air.
If you did the 383, you would be out similar money but not near as much fabing and changing stuff around as an LS swap.