If the pressures are similar in the 375 flanged and your wildcat the comparable velocities won't be that far off.

Barseness, a magazine rifle "looney" has suggested that velocity is increased only by one fourth of the volume increase. The volume increase of the flanged vs your wildcat is only ~6% thus a 1.7% increase in velocity expected with the 375 flanged vs your wildcat.

If you like your DR and have the brass--go for it!!