Here are some IMO cool T-shirts seen on ebay.

http://www.ebay.com/itm/70-Chevelle-SS-early-70s-Vintage-t-shirt-NOS-0059-Small-Medium-Large-XL-/170749111526?pt=Apparel_Merchandise&vxp=mtr&hash=item27c170ace6

http://www.ebay.com/itm/1971-72-Chevelle-t-shirt-Vintage-70s-XXL-XXXL-0143-/170740971378?pt=Apparel_Merchandise&vxp=mtr&hash=item27c0f47772

http://www.ebay.com/itm/1964-65-Chevy-El-Camino-Hooded-Sweatshirt-70s-NOS-Small-Medium-Large-XL-0160-/170751837244?pt=Apparel_Merchandise&vxp=mtr&hash=item27c19a443c

http://www.ebay.com/itm/1969-SS-396-Chevelle-t-shirt-Vintage-70s-NOS-0056-Small-Medium-Large-XL-/380394823536?pt=Apparel_Merchandise&vxp=mtr&hash=item58914c5f70

http://www.ebay.com/itm/1966-Chevelle-Early-70s-Vintage-t-shirt-NOS-0194-S-M-L-XL-/380394823501?pt=Apparel_Merchandise&vxp=mtr&hash=item58914c5f4d

This seller has a bunch of different kinds

http://www.ebay.com/sch/ronohio44/m.html?hash=item27c170ace6&item=170749111526&pt=Apparel_Merchandise&vxp=mtr&_trksid=p4340.l2562