Those old units (including Heathkits) are really historical pieces for the most part.
My best test generator is the Tektronix TSG170A. It does everything. Got it for 1 cent off eBay. (The shipping was more.) NTSC stuff is really coming down.
Here is the "D" version of the same generator:
https://www.ebay.com/itm/Tektronix-T...UAAOSw8xhdBK9R