Alco Models disappeared a long time ago. (The ad above was from the mid-1970s.) The company primarily imported models made by KTM (Katsumi) in Japan.
I have an HO scale Alco Century 430 that I bought -- actually, it was a high school graduation present from my parents -- in 1980. It cost $110. The model sold for well under $100 in prior years.
It was a pretty sturdy model, built with thick brass stock, but it was poorly designed with a driveshaft that used rubber connectors which eventually shrunk and crumbled, leaving the model motionless. (NWSL made a replacement drive system at some point, but that also was so long ago.)
Bottom line: Don't base your O scale aspirations on Alco Models. Avoid brass in general unless you are ready to fashion your own replacement parts. Remember, brass locomotives are handcrafted from brass sheets and usually lost-wax brass castings, not from diecast or injection molds, so replacement parts are uncommon, and most repair techs (with some exceptions, of course) won't touch them.
Also, 5 x 9 is too tight for two-rail O. It's OK for three-rail O using 48-inch diameter curves or tighter.