Can I put reverse cone megaphones on this bike if so what adjustments need to be made custommead

loosen of the axle /frame nuts and adjust the cone nuts for the bearings on the axle ( not to tight or it will feel like you are pushing up hill all the time)

The transmission linkage is either woprn out or the reverse gest cone is worn out.

If the rears are not adjusted right, it could be a problem. And they should be self-adjusting, although often the adjusters get frozen from rust, corrosion, dirt. To adjust them, you drive in reverse and hit the brakes. Every time you do this the adjuster should click-it has made one turn on the adjuster's star wheel. Do it a few times: reverse, press brakes; reverse, press brakes. If brakes were too loose, and adjusters were working, the brake pedal may brake better now-pedal may be higher when brakes are pressed. If not sure, peel off the rubber plug on back bottom of brake backing plate. You should see the adjuster star wheel. Use a screwdriver and see if you can turn the star wheel either way. If still not sure, take the brake drum off, pull the shoes off, and take off the adjuster for cleaning. They are very simple devices, only a few parts to them. If they need cleaning to free up, do so. Then use some high temperature grease, very sparingly, on the adjuster's threads. Put them back on, shoes, and drums, then do the reverse and brake again to get them adjusted. Should work great now. When you pull the drum off, you can check if you need new brake shoes- not likely, but check.
Good luck.

Reverse clutch pack problem .

Sounds like the cable has shifted, from the gear lever to the transmission there is a cable that puts the transmission in the correct gear. this cable is adjustable where it bolts onto the transmission and has probably moved

13mm nut on arm on driver side bottom trans pan mash emer brake put shifter in park loosen nut put trans in park tighten nut

put into 2 wheel and reverse truck cone type engagement in 4wheel sometime have to reverse to release

It sounds like the transmission needs service and adjustment. Typically you depress teh clutch and start the vehicle then try to shift into reverse. Try starting the vehicle, let the clutch out, then depress the clutch and attempt to put the vehicle in reverse. If it still will not engage reverse then you definately need transmission service and adjustment. There are several causes for this and they all require inernal repair of the transmission.

you need to readjust your cable.

Try adjusting your throttle linkage