I'd imagine manifold torque specs would be similar for all EJ engines of a similar size.
Intake manifold tightness - just guess by size of bolt / thread / common sense - get a feel for it with experience.
The biggest thing is not to over tighten /strip threads (use a ring spanner to finally tighten - rather than a socket and bar /ratchet. - just nip it tight.
Its not a critical moving engine component.
Have been working on engines for 40+ years and the only thing I use a torque wrench is on critical components like heads , big end bearings , main bearings, wheel hubs, main suspension components, crank pulley , etc
- don't even bother with it on a clutch pressure plate or when doing a t-belt change on pulleys / tensioner , cam pulleys - never had any failures.