In large scale this stops being an upgrade and becomes basic engineering. A 1:32 model fitted out with resin can comfortably pass a kilogram, and a styrene leg under that kind of standing load will bend given enough months. The listing includes metal undercarriage for the Douglas A-20 Havoc and steel struts for the Hs 129, shaped to drop into the locating points of specific kits, so the title tells you which boxing each set belongs to. Degrease, prime and bond with epoxy or gel cyanoacrylate.
Metal pays for itself twice over in large scale, simply because this is where models weigh the most. If the project is still in the planning stage, look through 1:32 aircraft kits and order the undercarriage in the same basket. Every scale in the range is listed under metal landing gear, and the fine detail of bay walls and gear doors comes from 1:32 photo-etched parts.