my ke20 went from 760kg to 860kg with the 4age/t50 setup. i think the 15" saab chasers would add a bit, motor, gearbox, seats, ke55 diff and front brakes a little heavier, surge tank and pumps, larger exhaust, larger radiator, brake booster. it all adds up.
i've since removed the back seat as its engineered as a two seater.
but also added turbo manifold, turbo, intercooler etc.
keen to remove the sound deadening and the interior trim and carpet and get some light weight 13"/14" wheels and see what she weighs.