Getting 90 HP from a 1275 engine is very do-able without breaking the bank, are you going to do it for a $1500-2000, probably not, but probably for $3000-4000 assembing yourself, and another $1500+ if a pro assembles it for you. If you want to to get to 100 hp with carbs, then big bore is the route you'll have to take, like a 1380cc, a very high level streetable 1380cc on carbs can get slighty over 100 hp.
Forced induction like the Moss supercharger can net impressive numbers as well, and can get to and over the 100 hp mark, but you've got the cost of the Moss supercharger to think about first, thats $3700 for starters, then there are other add-ons ,and you easily tie up $4000+ in what you need to do this. Ok so now you sprung for the Moss Supercharger engine, what sort of engine do you currently have, if you already have sprang for high compression engine using higher compression pistons and cut down head, already the supercharger is not going to work on that engine, forced induction require lower compression levels. The Moss supercharger was built with aprox 5-6 psi of boost, so it will work with say 8.8 to 1 engine, but not a 10.0 to 1 engine, and then if you want to look at the the higher boost pulley, now you are flirting with 10 pis of boost and really need to think about a forged 8.0 to 1 custom piston. Ok lets say you have factoy low comprsson engine now, if in good operating condition, then sure you can bolt the Moss supercharger on it, and go, but if you have a higher mileage low compression engine, forced induction will quickly tax your worn engine, so one fo the first things to consider wih forced induction is having a engine that suited to handle it, and if yuo need to rebuild to get there, you have to add that on top of the cost of the supercharger, hence the old saying, how fast do you want to go, and how much do you wan tot spend to get there.
The Moss supercharge ris the base for what dreams are made of though, I'm very thankful they took onthis project for the good of our hobby, because if you were to approach this in high level manner, you can have the same HP ratings as all out high compression race engine, but yet still drive ti down to the road to the grocery store, now doesn't that sound like fun
