Daz
You probably read that it was alot harder in one of my proir posts.Here's why.
I had a B21 in my car before installing the B230.I also knew (I thought) the engines were basically the same.I knew about the different rods etc. But here are the reasons the swap is harder with the B230.

1.The way most people have dealt with the oil pan difference on the later engines was by installing a B18/B20 oil pump and pan.The Early oil pump will not clear the crankshaft.Modification of the B230 crankshaft or the oil pump (or both) is required.

The balanced pulley on the B230 that someone (john sargeant I think) mentioned below will hit the swaybar.On the B21/23 you just unbolt the AC part of the pulley and the clearance is nice.

3.The water pump difference stated below is a problem also.The water return pipe that comes into the back of the pump has a bolt that holds it into the pump.With the B21/23 pump you can use a stock alternator adjusting arm.With the B230 pump you have to fabricate an arm.sounds easy but once you see what you have to do you'll realize that you lost most of the range of motion of the alternator (depending on the alternator you use of course).I messed with the alternator and BELTS (don't get me started) for a very long time when I changed from the B21 to the B230.

There are also smaller points like no hole for the ECT in the B230 block (easily overcome).The oil pump problem is also easily overcome if you have the engine apart.I didn't.I was dropping in a low mile rebuild.The crank could be very slightly machined (one of the counterweights) and rebalanced.The front pulley could be shaved and rebalanced (in theory,try finding someone to ACTUALLY do it!) It can basically all be overcome.just kind of a hassle and not as clean.The B23 is the way to go for fitment and stoutness.See my next post for some pictures