You need to find a copy of The Standard Catalog of Smith and Wesson, 3rd edition by Supica and Nahas. The Model 29 and it's variants take up a couple of pages.
Standard Catalog of Smith and Wesson, 3rd ed.
What serial?
Your serial number indicates that your Smith and Wesson model 29 was made between 1977-1978.
1994
100-1000 USD
@ 1980
The Model 29 is a 44 Magnum.
An engineering change.
Never made by S&W. The Model 29 is a 44 Magnum
300-600 USD
Impossible to answer without a serial number.
100-500 USD