Yes, Sri Gading is a chempejak. We're eating ChNa, or "Cheena" now. Like all chempejak I've tried, the leaves and tree characteristics, even the skin and size of the fruit, look like jackfruit and the flesh closely resembles chempedak. I've also planted Sri Gading (CH39) and Nangka dak (scionwood from Frankie). I think Frankie has brought in a couple more chempejak cultivars but Sri Gading is reputed to be the best of his imports.
I know of only three chempedak cvs in the US. CH26, CH35, and "Red", an orange fleshed cv. I think it was DurianWriter who recently sent in seed of a red and the "Durian" chempedak. I haven't had any good seedling chempedak in Hawaii yet.
Plant more chempedak and chempejak, they're awesome.