I work as an HVAC Mechanical engineer and i can say you are totally ok with the pictured set up but if your new stand goes in front of the return you will not want to block your return even with a gap and you should consider a different place for the tank
OR it would only cost a couple hundred to get a professional to move the intake for the furnace. look in the furnace room and see if you can think of a new good/easy/centrally located place for the furnace intake. then just call and ask for a quote to move it. worst comes to worse you could move the intake to high in the room near ceiling above the tank but you would do much better moving it away from the tank. both for the tank safety and your furnaces (just think if you go to replace the filter and that gross dust falls into the tank!!) if you are building a big tank then I hope you own the house so you can do this and if you are building your dream tank and doing it right and you are moving the duct you could even have an electrician place a new breaker with some GFI outlets on the wall for your tank since they will have to do drywall work. It would be an investment but your tank and your furnace would be much more successful if you did. oh but you would want to move the existing tank before they start work which you would have to do anyway if the new tank is going in this location.
just trying to help brain storm some ideas for you. know this one is extreme but compared to the overall cost of new tank and set up. moving a return grille location is not unreasonable.
Good luck!
the new stand was made bigger then the tank and will cover the intake. I noticed part of the intake screen has rusted any help appreciated?
