In the UK they do put K-series[0] engines into the MGB.
[0] The K-series is the descendant of the T16, which is the descendant of the M-series, which is the descendant of the O2-series, which is the descendant of the O-series, which is the engine that we /designed/ for the MGB, but never was put into the MGB before it was canceled. The O-Series instead went into a bunch of work vans and other hateful boxes instead.
So he might have sort of been right. But he was probably still a royal bullshitter.
Descendant only in the fact it came later. The engines share nothing from memory. The K series was an all new small capacity engine (1400cc) on release. Compared to the O, M and L (diesel) it's a fully aluminium block and head with steel damp liners. The K series had its bore and stroke upped to bring it to 1800cc after launch, along with adding variable valve control with the VCC engine.
The two engines share very little in common, the most frequent thing being they're normally both attached to a a PG1 gearbox.
K16 was the motor in the early Lotus wasn't it? I know from my 214 days you could 'easily' change the cams to give more power. I assumed this was what they did for the MG versions. I enjoyed working on the K8 and K16 engines.
[0] The K-series is the descendant of the T16, which is the descendant of the M-series, which is the descendant of the O2-series, which is the descendant of the O-series, which is the engine that we /designed/ for the MGB, but never was put into the MGB before it was canceled. The O-Series instead went into a bunch of work vans and other hateful boxes instead.
So he might have sort of been right. But he was probably still a royal bullshitter.