As noted in the post, the Triumphs are broken down to individual models, whilst most other Marques have a more generic Iconic colour. Iconic Marque colours rarely change, for instance, Audi & Mercedes have always been silver, Ferrari always Scarlet. Triumph seems to have been an exception.
As for the black bumpers, This was the best photo I could find to show off that awesome Magenta. There's a few things that don't look quite "right" about this spit, one of which is that whilst it appears to be a 1500, the licence plate colour is only legal for a Mk4 or earlier, and it has a year letter G which would also indicate a Mk4, but the spoiler says 1500, as do the Turn Signals. Also the windshield rubbers should have chrome inserts no matter what year, and the Wipers should not be colour matched.
I'd also say that was a 1500, a genuine G reg would be a 69 MK III (my very first car was one!) I' also take issue with Magenta being the iconic colour for a spit, GT6 maybe but its a pretty rare colour on a spit, my MKIII was Pageant Blue and the 1500 was a very similar blue to the one pictured earlier although I think that one started out as red and the blue was shockingly, a Ford colour, although I've been in therapy and gotten that out of my system now. I did have a hardtop for my 1500 in Magenta although it clashed terribly with the blue.
I'd say the iconic colour for a spit was probably BRG for the later models and possibly blue for the earlier ones although that nasty shade of baby-**** yellow seems to have been a very popular colour for later models, something went very wrong with peoples heads in the 70's, must have been some very iffy drugs around then! I will however support your statement on the fugly federal bumpers, after all, them lot also ruined the MGB with those horrible rubber bumpers and raised ride height.
Anyway, enjoy your Spit, they are great fun, I loved mine and I have plans for another one as my retirement project although I'd like to fit a modern engine, possibly an MX5 engine and six speed box although the biggest problem with fitting a more powerful engine is that the diff is made of cadburys dairy milk chocolate and melts into cocoa if you get anywhere near about 150 hp. Theres a huge amount of tuning parts available for them, from uprated suspension to unleaded tuned heads, electronic ignition and so on. My 1500 actually had a tuned 1300 in it as they rev much better than the longer stroke 1500 and with just a little work easily make as much power, mine had bigger SU's, a home ported and polished head, tubular header, K&N filters and a free flow exhaust (which was headache makingly loud but hey I was in my 20's and loud was good, especially under the low railway bridge on my way to work!)
Oh and my 1500 was moved in the back of a 7.5 ton truck, although at the time it was slightly dismantled for a resto that sadly never happened due to lack of a garge at my new house, it got sold on to someone who finished the job.