Timing belts are easy , if ya know what your doing and have the right tools
for the job.

The biggest thing you need to be aware of is this, there are NO SECOND
CHANCES if you F**K UP, the VG30E engine is an interference engine.

By that I mean , if the belt is installed incorrectly and the cams are not
kept in perfect time with the crankshaft it will surely bend the valves in
one or both of the cylinder heads, kinda like that old Beatles song
Maxwell's Silver Hammer ... Bang Bang  Maxwell's silver hammer came down on
his head... and made sure he was dead (get it   ... :-))
, in other words you just screwed the pooch and the car won't run until the
cylinder heads are pulled off the the bent valves are replaced.

It's doable considering your experience level. I did a 93 GXE at 120k
miles a couple of years back.

As well as replacing the belt I put on a new belt tensioner and
replaced the water pump. At 143k I would go for a new water pump since
you will have easy access to it. The tensioner is optional.

Can't remember the details but I used a Haynes manual as a guide. You
can find instructions on the web, do a google search.

Main task is removing the timing cover. If I remember correctly I had
to remove an engine mount to get it out or to get access to a bolt.

Loosening the crankshaft pulley bolt is difficult. I used a ratchet
with a long extension supported at the ratchet end on a pile of bricks
and hit the ratchet with a 2 x 4.

Hope this helps.

Al Moodie.