It is indeed possible to uprate the ohv engines.
There have been articles published in Club magazines over the years.
One of these featured a Janspeed Toledo. It could be made to make over 100 bhp but its fuel consumption was chronic! Think Jaguar XJ6
.
Re the cornering,
there is little point fitting uprated springs/dampers unless you first replace the worn out suspension bushes.
I have Superflex bushes and standard suspension c/w 175/70 tyres on Minator alloys on my 1850, the result being a nice
predictable car. People do comment often on how well it corners.