Did exactly this about 5 years ago. Silvertop had bit the dust at a trackday and it was cheaper to drop in a new Blacktop instead of either rebuilding the old engine or risking another (by then) old Silvertop.
It was pretty much a direct swap with a few exceptions, will try and be as accurate as my memory allows.
Off the Silvertop I used the following with no modifications:
Thermostat Housing - Blacktop one is useless since it has no bosses for senders and is made of cheese
The following parts need some modifications:
Dunnell Sump - bought kit of parts from Scholar engines to fit Silvertop windage tray to Blacktop, cost £15
Oil Pickup - had to modify slightly to rotate it on the pump, easily sorted in the garage
The Off side silvertop engine mount fitted strait on, the near side need a simple mod to the top bolt area, easily done in the garage. Mine are Dunnell/Whiting mounts, others may need different mods.
Alternator - had to make a plate to allow the Silvertop bracket to bolt to the Blacktop, garage job. Bought Raceline idle pulley kit kit, other are available but it looks nice. Only works with engine covers off but there is no way a Blacktop will fit in a Caterham with the front covers on.
Had to replace some hoses but which depends on which cooling system you use.
I fitted the Silvertop cam cover, direct swap and looks way better than the Blacktop plastic fantastic.
Used the MBE management directly off the Silvertop. Minor remapping required.