Frame as shown fits 24" wheel set. Serial number single letter "L" indicating pre 63? Sew pictures of kickstand tube for what looks like a repair to the fender bracket.

 These 24's can be fitted with a 26" wheel set if you grind the rear drop out some and install the rear wheel with the tire and tube deflated. It's kinda sorta like a donked out bike in a way and I have done it! The ride is smooth with a bent 26" fork set up.