Axle

hi all i just bought a 79 brat with NO rust ,bad paint but still . anyway it has a bastardized ej81 in it . i know it will need a carb rebuild , it came with 3, it has two different heads on it one looks like it should be injected the other not .from the road dirt and bit of oil it would seem to have been like this for some time .but will this ever work right ? it also cam with 2 non injected heads how hard is it to change out these old subi heads ? or if someone has a link to some where i can find out it would be helpfull