Bathroom Upgrade

Upgrading bathroom to ADA accessibility and repurposing an adjoining closet to house a gun safe @ close to 1,000 lbs. My weight is 460 lbs +/- a little and a power wheelchair that’s in the future I’m quite sure @ 350 +/- lbs. Area roughly 14’ x 14’ but also thinking about areas of travel (hall ways). Feel I might need to reinforce the 2” x 10” floor joists. Doubling them up is not practical, electrical panel in the basement area in question so most of the electrical wires run through the joist as well as the plumbing (hot and cold water, hot water return and DWV), as well as base board hot water heat supplies and returns along with central A/C ductwork and returns. Joists span 14’ - 16” on centers. Gun safe 33” running the same way as the joists and will be centered approximately 3’ from the end where it bears on a 12” block wall (not sure if it will hit 2 or 3 joists). Along with any suggestions I’d like to know how much it will add to the strength of the 2” x 10”s by “sandwiching” them between full length (14’) 2” x 4”s (both sides, near the top), bonded with “liquid nails” or equal and nailed (also would screws or lag bolts be stronger). I worked in structural steel design back in the ‘60s, don’t remember all of the forces but I think sheer and deflection (bending) are all I need to be concerned with. Oh yea, house custom built in 1976-77, and I believe joists are Douglas Fir. Bathroom floor to be SLC w/mesh and ceramic tile (possibly heated w/ “WarnlyYours” electric floor heating system). Don’t know what else I add.