I've been whitetail hunting every year since 1966 and have never felt under-scoped with a 40mm objective, and my most-used whitetail rig sports a 38mm bell.
After all, you use your 50mm binos for spotting and evaluating the trophy. The scope is only used to facilitate the shot AFTER you've already sized the deer up with your bino.
As to the OP's question, may I answer neither? I would look at a Howa 1500 or a Marlin X7.
"The devil made me do it the first time....second time I done it on my own." Billy Joe Shaver.