1. I have one that Ive restored, it was my Novice rig.
2. HW-7 is not a boat anchor. Boat anchors are large, heavy radios. Just because its old doesnt make it a boat anchor.
3. That MOSFET is a combination of RF amp and mixer. There are no switching functions.
4. That part number is for a digital switch device (digital bus buffer), has no relevance to this question.
4. The "front end" is a dual gate MOSFET, the replacement is supposed to be BF991, I recall reading someone had used one, I have not since the original in my rig still works. This device has ESD diodes built in.
5. If one finds the "original" MOSFET advertising the SHORTING SPRINGS HAVE BEEN REMOVED, DO NOT BUY THEM. Some Hucksters had advertised that... those original MOSFETS were extremely sensitive to ESD and just the act of removing the spring can destroy it, unless its connected to the circuit. Was there, did that, blew the first one up.
If youre going to be in there working on it, a couple cautions
a. DONT reroute the long RG 174 cable from the TR relay to RF preselector, its routed behind the circuit board for a reason.
b. Remove the TR relay and look for corrosion under neath.
c. Ignore the Hams websites discussing design changes, especially the break in transistor circuit, because the information is wrong. The fault in the break in circuit is an old leaky capacitor (or just a bad transistor) and the advice to change resistor values WILL apply DC voltages in excess of the ratings of that transistor. Beware when Hobbyists think they know more than the Engineers that design things originally...