There were two types of firing pin used on that model. Would need to see the bolt, but we have the pin. gunshop@nctv.com
gunpartscorp website has a cross reference to find the originial make and model, and usually his firing pins.
Numrich Arms
Try e-gunparts.com
Gander mountain usually has them.
You could ask gunsmiths, you could check the gun shows, you could try e-gunparts.
theres a website j.c. Higgins model 88 has the exploded view with parts list
You can find it on the Crosman web page. The JC Higgins model 180 was made by Crosman Air guns. See the link below
Try e-gunparts.com
Marlin Firearms
I have quite a few. sales@countrygunsmith.net
www.histandard.info
your J C Higgins model 90 was based the J C Higgins model 88 and is some what harder to find model a model 90 in NRA excellent condition is worth between 125.00 and 175 .00 the model 90 was made from 1958 to 1962 by High Standard manufacturing for Sears