Have you tried looking on some of the internet gun auctions for a later manufactured Browning A-5 mag that was made with choke tubes..??..

Another thing to consider... I have guns with the safety in front of the trigger guard ( Win m12 and M59) and I have guns with the safety behind the trigger guard ( Remingtons and Brownings) and I have never had any problem switching back and forth at will, even on the same hunt..... You might adapt faster than you think you will..