get the mallory pvc caps from Alyn and toneslut tranny from Moose and send them to Nik for your build he will happily do that for you, that way you recieve it complete and it's ready to scream right out of the box!
I have both the 1/2 power & MV on my Liverpool. I am no expert but in my limited experience the 1/2 power does not deliver a useful decrease in volume and the MV does not give a pleasing tone. I have never heard a true Trainwreck or even another clone but my Liverpool sounds great to me cranked, it's really something else, but I haven't been able to find any pot or switch setting that sounds good to me when using the 1/2 power and/or MV. I can't say why, but my Liverpool is as loud or louder than the 50W amps I have to compare it with and I will not be able to use it at the house (if any one is home!). I did build a DIY Airbrake as well and that does make a reasonable volume difference with less of a sacrifice in tone, but it's just not the same as straight-up with the knobs really twisted. I guess these amps are just loud, really f'n loud, and not that flexible as to where you can set the volume. I think you just need to be prepared for that. The up-side, however, is that you'll be plotting for every chance you can get to crank it up! I'm sure my kit is nowhere near what it could be and probably light-years from the real deal or even a good clone, but to me it kicks ass and it's friggin' dimed whenever I get the chance.