I can't say for sure because every company seems to route at least one tube different from other company's...but I have used headers that fit the same cars listed for fitting this header on the 73-87 2wd trucks. The headers I used were both Hooker and Blackjack for 70-81 Camaro, 75-79 Nova, 73-77 Chevelle, 71-77 Caprice/Impala and fit fine in the truck chassis.
Just looking at the header in the picture it looks like it should fit fine, especially since it fits the cramped engine compartment of the 78-87 metric chassis.
At 357 cubes the 1-5/8" header primary isn't hurting you unless the port opening is bigger than that and making a bad mismatch, but the 2-1/4" exhaust could well be a cork. The 1-3/4 primary header could cost you some torque.