Hi ya there The long Build
there is no harm in doing what you suggest, earthing off to the radiator, as long as its the 'old type' radiators with copper pipes and they have all been earth bonded.
With regard to your Electronize kit build, you will find a mega difference in components between Electronize and ACTion kits. Electronize have 33 resistors - 4 diodes - 2 ICs - 8 transistors - 15 capacitors and, if you are building the one with the BEC in, its also got the BEC module - which is just a small component and nothing to worry about.
To be honest, there is nothing too difficult with these kits, there is no real need to use an anti-static tray - to be honest with you I have never used one. The only 2 different things that I do is, the Electronize kit is not supplied with an IC socket, for the main IC, and they are only coppers to buy. Also, I use a crocodile clip as a heat sink on all the transistors.
Its amazing isnt it. That little chip in the ACTion speed controller, does away with all those resistors, transistors and capacitors :) than the Electronize kit, and they both do the same job.
A good magnifying glass is also very handy for building the Electronize kits.
Aye
John E
BLUEBIRD