I was taught in the 1970s to shoot revolvers using a strong hand grip with thumb pointed forward with support hand thumb over top of strong/shooting hand, which turns out to be similar to Weaver’s; with an extended strong arm which is today similar to Chapman’s. This worked fine with J frames and K frames 38 Specials, but with 357, 41 and 44 Magnums I preferred my support thumb on top of strong hand thumbnail (one gripping the revolver), and with a stance which is basically an isosceles.
Attached is picture of Jack Weaver shooting his revolver, notice his extended right hand thumb and support left hand thumb wrapped over on top of strong hand (btw, Miculek recommends a thumb over grip on S&W J frames).
These techniques have worked for me and are basically engrained good habits.
How do you grip your J frames or competition revolvers?