Looks interesting enough. Think a 4x10 may be an overkill in a HDB flat. A 2x10 would take less space and be portable enough to carry around if need be.
I've got a HA3500 and a 410xl in my HDB flat, as long as you don't turn the volume above 1, it's fine
What I like about it is that I can have a good clean sound without getting any distortion from the speakers.
I used to own a Yamaha combo, which I personally find very good, but at louder volumes, I find that the sound gets a bit distorted.
With the 410xl cab and the 3500a head, i don't get any distortion at all, which is what I really like about it, plus it's a hybrid amp which I swapped out the 12ax7wa tube to a better sounding JJ ecc83s tube, sounds even better now
Just the main thing with the head and the 410xl cab in a HDB flat, don't turn the volume past 1, it's loud enough, won't annoy the neighbors, and you can get some good clean tone without any distortion from the speakers.