The
Hammond 1441 steel chassis approach is full bends with spot-welds and complex woodwork. The aluminium 1444 chassis can't handle heavy weight though and I've had the spot welds break.
It helps to take a sheet of paper and some paper/cardboard cutouts or cutout photocopies of the bigger parts, to do a layout and see if there is enough room.
If you're using turret strips, sometimes they'll end up in a tight spot or you need an extra one. Coupling capacitors to EL34's might be large size and can take up more room than expected.
I think important is cooling, so the O/P tubes are not too close together 1" spacing seems small. The input and phase-inverter's need metal shields especially if using a tube rectifier. Several hundred volts swing near them and they will pick that up on the plates.
The worst part with a power transformer in the middle, is where the RCA jacks are. With both on one corner, one channel will need a long shielded cable run so the extra capacitance can unbalance the two channels and add something to fix that.
Stainless steel is hard to work with.