Interesting -
"The car's engine was a derivative of same found in the Fiat 600, but with an enlarged bore and stoke. Added to this was a special DOHC cylinder head that used hemispherical combustion chambers and an increased compression ratio. Along with an improved intake and exhaust the 1000 Biabero could produce 91 bhp - nearly 100 bhp per liter."
All those fancy parts, and they couldn't pull 95.1 hp? 
Uhhmmm . . . . . it was 1960. Need I describe the school uniform I wore (unwillingly . . . .) to "Our Lady of Perpetual Guilt"?

I don't think you were even born then . . . . . .
I don't know about you, but, I've learned a couple of things since 1960:
A/ Most of my relatives are a**holes
2/
ALWAYS, spit 'downwind'
d/ Better to pick your friends than that nasty looking, re-occurring scab . . . . . . .
Sooo, let's look at engine numbers for 1964, 3 years
AFTER you were born . . . . . .
Before the end of 1963, a long nose variant was introduced with a new body from Sibona & Bassano. It featured a fiberglass, front-opening hood that replaced the fixed aluminum unit. This feature was standard in 1964, with a slight power increase to 104 bhp @ 8000 rpm and a top speed of 220 kph. (136.7014 mph . . . . . .) Although the model was updated, focus shifted in 1964 to the larger displacement cars, especially after Division 1 was increased to 1300cc. Read more at http://www.supercars.net/cars/201.html#bE0Q33AkUFQBRldd.99a special DOHC cylinder head that used hemispherical combustion chambers and an increased compression ratio. Along with an improved intake and exhaust . . . . . . Hey Martin!! Are you looking for an engine guy? Pretty sure I can get 115/118 bhp/litre out of this little Italian grenade.

Would be Fiatboy