To be fair, a lot of 'Mechs in 3050 got beaten with the "Questionable Upgrade" stick. Enough that I get a fair amount of fun taking new tech and actually making sensical upgrades.
The HBK-4G in particular has quite a few wonderful options available for upgrade. Switching to double heatsinks and dropping down to ten is a no brainer, as it takes up a grand total of one more crit on a frame that's got a couple dozen left over anyway. Keep the AC/20 or switch it for a Gauss Rifle, whichever you prefer; when you drop the three new extra heatsinks, you've got a few extra tons to buffer the upgrade, or to add some more ammo to the AC. The -4G is one of the very few 'Mechs that gets a no questions asked upgrade to XL engine, as you can bump the speed all the way up to 6/9 if you keep the Gauss Rifle with two tons of ammo or the AC/20 with three. In 3050 ER lasers besides the large aren't available, so keep those the same. Endo-Steel and Ferro-Fibrous are pretty much completely unnecessary, and the result is a 6/9 heavily armored Gauss Rifle and some lasers. Slightly less powerful bubble of doom, but it's still a headcapper, and now it reaches out and touches someone at 24 hexes. Or you can just have a faster AC/20 with the same armor and some more ammo.
3050 designs are just headscratchers.