Nice job restoring it to a convertible. Those wheels did not come from that kit for sure, but I don't know the Tom Daniels kit well. I bought that same '58 Impala kit at Sears when they used to sell models. It's the first of the AMT foldable boxes which I think began about 1971. Should have a T273-225 kit number, I think. -225 means $2.25
Walmart in Hudson, NH carries model car kits but the Walmart in Hudson/Marborough, MA does not. About a 30 mile separation. Last time the Massachusetts Walmart had models was in the ERTL checkered box days.
Tom, you are correct. It has to fit before paint and assembly. I am guessing that maybe there is a 5% shrink in a resin copy versus original. Even still, the body is thicker in the resin that original and it is not consistent in thickness. There are 2 Modelhaus '60 rear bumpers. One is the Impala shown above used in the AMT Craftsman Nomad kit. You need to order the promo '60 rear bumper for the Nomad which has 4 tail lights.
While 1975 is the first year rectangular headlights showed up on new US cars, I believe the Federal law changed a few times over the years . It dates back to 1940 when a new law stated that only 2 round sealed beam headlights were allowed. In 1957 it was revised to 4 round headlights and again in 1974 to allow square shapes. A lot of the European spec headlights used replaceable bulbs that did not fit the law. Headlight covers were allowed in 1983 with replaceable bulbs. This allowed more aerodynamic car body shapes for efficiency. Those rectangular shaped bulbs on both Olds were illegal until 1974.