Hi I bought a 325is 88 std. like 2 months ago that didn't start, slowly I have put all the pieces tougether AND Finally

It starts fine, some times it misfires but nothing serious, probably the slugged oil that I haven't change still . I put a new fuel pump and sending unit, change sparks from champion to some bosch 2ble spark, and change cables. did some fuel lines on the way and it sounds pretty well. The car was parked on a porch since 2005. . I need to fill some air on one tire to try and give it A RIDE!! BUT I CHECKED on my gears specially Reverse since I havew it spoted in a tight space, and it won't engage on reverse. All other gears engage and front it goes, So i belive it will run OK on 1,2,3,4,5 they all engage but NO REverse what could be the situation ?? Does anyone experienced similar problem??