'kay, my tongue was a bit in cheek there but to Chrispy's point - finding the bits and paying for the resurrection of a smithereened Twin Cam can be a long and expensive process so if you can find an alternative that works - fine by me, as long as it retains SOME of the character of the original.
My 1960s "classic" (1966 Cortina GT) had a Twin Cam in it when I bought it - the previous owner had stuffed a 1.8 Fiat Twin Cam in it, giving a bit more hp than the Lotus Cortinas I had owned
and it had a 5 speed.
Just didn't quite have the 'bite' so I finally went with, again, a similar engine, 4 cylinders, twin cam, high revving and decent sounding, oh and 6 speeds....and there is no way on God's green earth that I could have obtained a Lotus Twin Cam for what I paid for the F20C I installed.
If I ever get back into this era of Lotus (and it will be a Plus 2 if I do) ideally the car will be needing a new drivetrain and I will oblige by sourcing a Japanese drivetrain with 'adequate' power and inherent reliability.
And a 5/6 speed 'box