It does look a lovely installation though. Would be even nicer in a Chevette.
V6 is shorter than a 4 pot too, and unusually narrow V angle helps a bit too as long as you don't have a steering box to get around...
the problem with engine swaps in a lot of fifties cars(MGB underbody wasn't new) is that the front chassis rails sweep up and inwards to mount the suspension. That doesn't really matter with a tall, inline engine but is right where the exhaust manifolds need to be on a vee motor. DOHC heads make that worse, as do the very wide Rover heads - Rover V8s are only common swaps in the UK due to their ubiquity, they're actually long, tall wide, underpowered compared to their bulk, and not very durable. And the 'alternatives' were even worse; Essex V6 for example.
When comparing the weights, don't forget the gearboxes: four speed with an additional chunk of overdrive both in cast iron compared to a shorter aluminium cased five speed. Swapping the massive V6 flywheel four cylinder one would make another difference. Although we've fitted the back of the engine in the stock location, the front pulley is about where the front axle line lies. This changes the weight distribution, as the car currently sits higher than normal on its standard front springs.
MGB suspension is double wishbone front with decent geometry, and there's nothing wrong with parallel leaf springs. The biggest problem is that it's all a bit cramped under there. This car is intended as a GT, so with appropriate front springs, thicker oil in the front dampers and telescopic rears(Escort ones I bought by mistake 20years ago) plus 4pot calipers on bigger, vented discs(an off the shelf upgrade as Ian wants to keep the stock alloy wheels) it will be plenty good enough. The car's small size, light weight(even small modern cars are ridiculously heavy), impressive power to weight and torquey power delivery will make for seriously usable performance. If it were my car, I would have used a 2.2 four cylinder.