Like Nevada said;I'd start with 18.5gr of 2400 and work up.Not that your load is too hot considering you'll be using 220 instead of 240gr but you don't know what kind of mileage your 29 has in the body and since it is a pre E package,I'd start low and work up.
That's exactly the situation I went through 3 years ago and that .44 Mag still gives me excellent service.