You can get an insane level of power from a modded bug engine. Ported dual port aftermarket heads, compression, cams, dula carbs or injection, billet crank and rods...then there’s the big bore kits.
150HP is easy sans Turbo or the sauce. With boost, the only problem is keeping the factory block together. A fully aftermarket motor will hold hundreds of HP. The off-road guys pull 150 all day long and keep it together under the pounding of Baja.
Things have really evolved in the 25 yrs or so since I was building air-cooled VW’s. WOW!