18LE is the LB/LD Astra/N13 Pulsar engine, C20NE is early SOHC Calibra, 20JD is the Camira JD 2.0 engine and the X20SE engine I believe was used in the Holden/Isuzu Frontera. All these engines are GM Family II engines and are all SOHC. It's possible that a C20XE or C20LET head may fit (both are DOHC, the LET is the turbo head, but very hard to find in Australia, the XE head is off the early DOHC 2.0 Calibra), just as long as you get the supporting bits to go with them. Also, the C20XE/LET often used distributors for spark ignition and where these would mount, foul on the firewall in a RWD engine bay. Later heads from the X20XEV, C20SEL, C22SEL and Z20LEx engines may also fit on (X20XEV is late Calibra 2.0 engine, C20SEL/C22SEL are JR/JS Vectra engines and the Z20LEx is the turbo Astra engines).
Only thing is, I don't know if the external dimensions of the C22NE block are different than those of the other Family II engines (ie taller or wider block), but if they are, you're going to need to work out if you need a longer timing belt. Forged pistons, C20LET/Z20LET pistons might work, as they're all 86mm bores. Rods, I don't know how you'd go. 2.0 rods are 143mm long, 2.2 rods are 148mm. However, apparently big end bearings are the same across the 2.0 and 2.2s.