I'm sorry to say there is no easy way to do this, plenty of hard work and a large tub of elbow grease required.
Over the years I have tried various ways of cleaning frames and engines and following works best for me.

You will need a cleaning fluid, something like Muc-off/Jizer/WD-40/Duck Oil.
Spray the cleaning fluid of your choice on the frame/swingarm and start cleaning. I use an old / wife's toothbrush to scrub the muck out of the nooks and crannies.
Another favourite of mine is a rag wrapped a round a small flat screwdriver for cleaning out hard to get areas, thought you have to be careful the screwdriver does not end up poking through the rag and scratching you frame/engine!
Wipe of all the excess cleaning fluid. I would then give the frame and swingarm a covering of alloy wheel cleaner to get rid of the last remnants of muck etc. and finally wash this off with water.
Dry of the frame etc. I would then buff them up with some car/bike/furniture polish to finish the frame and swingarm of nicely.
Luckily NSR frames and swingarms (Are MC28 swingarms just cast?) are hard anodised as standard so they clean up really well.
Remember, tape over or plug the bearings in the swingarm / frame with rags etc! Though after 20 years, unless the bearings are super smooth I would be replacing them.

If you are unlucky enough to have a frame that has had the anodising stripped off, I would still do the same as above but finish of the frame using Scotchbrite pads.
In my opinion, you do not want to have to have the frame blasted unless it is in very poor condition.
I would start of with a red/burgundy coloured pad and finish off with a light grey coloured pad.
Do this by hand keeping the 'grain' running in the same direction, i.e. running along the length of the frame spars. This is not so important on the cast sections of the frame or swingarm.
Again, cover the frame with alloy wheel cleaner and wash off.
Finally, give the frame a light polish with any car/bike polish. This will give the frame a clean look, but not too shiny.

For the engine, it's much the same as above, although I don't use the alloy wheel cleaner. I have been know to polish the crankcases though...
Strip of as much of the ancillaries of the engine as you can and clean them separately.
Remember to tape over or plug the exhaust ports and carb rubbers with rags!

It will be worth the effort in the long run! In my opinion there is nothing worse than a bike with shiny bodywork and a manky engine/frame/running gear!

I hope this helps.