I'm not an "insider" at all, but my educated guess is that this is very problematic.
The company was sold in 2009, & I heard the US construction operation was closed 2010. This greatly reduces likelihood of a cache of parts being held somewhere.
Your guitar is three decades old. While the HB-35 has indeed been around all that time, its design has been reworked repeatedly; a present day neck might not even fit a 1986 -- the neck pocket might be entirely incompatible.
While an excellent guitar, its value tends to peak at ~$750, even for a 1980s MIJ. The cost & effort of replacing a neck on a $750 guitar is questionable, at best.
Simply removing & regluing a neck can cost $600 or more.
A luthier of any skill can take a compatible neck, & carve a heel that will fit securely in your guitar's neck pocket. This will cost $50+/hour, & take 5-10 hours of benchwork before it can be installed.