To have a fully working amp within a Month and minimal "new variables" or "unknowns" , out of your latest options I would pick the bridged TDA7294 option.
Why?
Because apparently the PCBs are available.
Not a full kit (which would be great for a first build) but the most complex part of it.
Components are standard and cheap, a PT will be easy to source.
If anything Antek probably has a suitable one, no need for filament windings, etc.
If not exact match found, pick one 2 or 3 Volts lower, which is safer.
Heatsinking?
Follow what original project suggests and if it says nothing, copy what other bridged or stereo 7294 projects use.
One BIG problem for DIYers is sourcing all parts, so let's keep that simple.
You'll need a suitable chassis.
Commercial ones are available, DIYAudio offers some nice ones too, and some matching heatsinks too.
If not, just as an example, my very first amps were built on local shop made ones.
Since I come from a rural town in the middle of the Pampas, all I found was the local tinsmith, a guy making food and water holders for hens , pigs and cattle, drain gutters, etc.
He had the necessary shears and folders 😄
Somebody above suggested a HVAC shop ... same thing.
Or maybe somebody doing bodywork for trucks.
He made me a U shaped chassis out of 1.5mm (1/16") aluminum.
Not rigid on its own but I screwed in right and left sides made of hardwood.
The resultant box was rigid.
Early Marshall chassis were built that way 😲
Notice the upside down U shaped aluminum chassis, bolted on both ends to a cast aluminum block for rigidity.
I suggest aluminum over iron because it does not
need special finishing, does not rust, is easier to drill, punch, file, etc. because it's softer, etc.
The option would be to clone a commercial amplifier, such as the Yamaha 100.
Excellent amps, but you would have to design a PCB from scratch 🤷🏻
Which in general requires debugging/troubleshooting/tweaking.
Fine for a commercial product which will sell hundreds or thousands, not so much for "just one"