The non HO motor has a 1-5-4-2-6-3-7-8 firing order. The HO motor has a 1-3-7-2-6-5-4-8 firing order and a reverse rotation water pump and front cover. All of the HO motors (except 84 and 83 mustangs) have roller blocks. The non- HO motors are non roller except for a some of the models made in the 90s.
The stang is definitely a roller. Stock injectors are 19 lbs. Im doing a 70mmtb/75mm MAF sensor calibrated for 30lb injectors, but I'm doing a HCI swap first. (I have a 95)