I think forum member "Alga" also weighed his running gear & got similar weights as you.
Most of the completed cars have come in weighing between around the 530 to 650kgs & thats with a full tank ( requirement for when its IVA tested).
It still gives a very good Power to weight ratio whatever engine is used & gives sprightly performance
I,m hoping my own car will be around 540kgs when tested , I weigh 71kgs so all in around 610kgs, not bad when you consider the donor vehicle weighed approx 1250kgs
cheers
andy