Didn't check the forum for a while. I think I have a pair of original steel sidecovers that I could sell, if you perhaps don't like fiberglass.
On my Morinis, I just used a tiny maintenance free 4Ah 20€ scooter battery, and it proved faultless for four years.
These early Morinis are such beautiful bikes, I don't think they could get more classic 70's.
The 80's model had a slightly different frame (bent around the front cylinder, gets closer to the engine - you can see the front mount is shorter). Supposedly a little better, but probably nothing a normal rider would ever notice (the oldest Morini twins handled very well anyway). The 70's Sport models had (compared to standard/strada/GT) a more aggressive camshaft, high compression pistons and slightly different jetting, besides clip on bars and a different seat (not much else). The 80's models had (as far as I know) the same engine as the standard model, the only difference was a more aggressive position with the low bars and styling. That said, the standard engine is neat too, perhaps slightly more torque compared to peak power, but not really that noticeable (it's still just a 350, they all made around 100hp/litre or more, really decent for the 70's - the new V7 and many other completely modern retro bikes do not come close).
I rode a Benelli Tornado 650 with the same (grimeca?) front drum (double sided single leading shoe) as the first series Morini Sport. I also own a '71 V7 Special with the double sided 2LS drum like the V7 Sport. As far as I'm concerned, both stop alright. The Morini would probably stop a bit better, since it's a very light bike (I think only around 150kg, the Tornado at least 1/4 more, the Guzzi even more). Overall, drums aren't that bad, problems happen with continuous braking (worse cooling). Those Grimeca discs Morini used were quite odd - hard chromed and grinded surface of a steel disc. Supposedly great braking surface until the chrome wore off (but I think it has around 70 HRc, really hard and durable - most commonly, it flaked off due to rust and age).