Building the whole ALU module on one circuit board would have taken less space than splitting it and adding all the wire links.
It's not normal to use jumper links with pin terminal ends for soldered interconnections, just normal wire stripped and cut to length as required.
Re. the FPGA, I've never used one for anything like that so I do not know all the possibilities that could work.
You would need one with RAM included, rather than a gate-only type.
An EP4C115 would likely be suitable; some people have built PDP-8 emulators using the DE2-115 development kit which uses that device.
eg.
Order today, ships today. P0059 – EP4CE115 series FPGA Evaluation Board from Terasic Inc.. Pricing and Availability on millions of electronic components from Digi-Key Electronics.
EP4CE115F29C8N Intel / Altera FPGA - Field Programmable Gate Array FPGA - Cyclone IV E 7155 LABs 528 IOs datasheet, inventory & pricing.
Or a Xilinx Spartan-3E device - again, that has enough capability to use for a microcomputer emulator.
The dev kit for that:
Nexys 2 (Legacy) The Nexys 2 is now retired and no longer for sale in our store. We recommend the Nexys A7 FPGA as an alternative. Nexys2 circuit board is a complete, ready-to-use circuit development platform based on a Xilinx Spartan 3E FPGA. Its on-board high-speed USB2 port, 16Mbytes of
I suggest that if you are considering anything like either of those, you wait for a development kit to appear on ebay at a sensible price!