If it could be bored any further I suspect Renault would have built the Sport 2 litre version with a bit bigger bore and a bit shorter stroke. With its already long stroke you wouldn't get any more bhp by stroking it even further, because you'd have to reduce the maximum revs.
The F4R looks like an engine that was originally designed to be a maximum of 1.8 litres, that has already been pushed out to its engineering limits by taking it to 2 litres.
That said, look what Toyota did with its 1.8 litre motor. It was designed as a 1.6. They stretched it to 1.8 by putting a relatively long-stroke crank in it. Then they wanted a performance version, which was a problem because it was already too long-stroke to rev hard, so they produced another version of the same engine with a shorter stroke and bigger bore. They got the bigger bore by casting the block out of a metal-silicon composite that pistons could run directly in without liners, which let them run a bigger bore with the same bore spacing.