If it was overgrown for some time your neighbours may not remember! In that case the soil has had a nice rest for several years, so some soil bourne problems may have fizzled out. Unfortunately, there are few that you can see when you dig, except perhaps eelworms that love potatoes. You will only find out if you have clubroot when you plant something from the brassica (cabbage) family, if clubroot is in the soil the plant roots are swollen and bobbly, and the plant fails to thrive. You can minimise the risk by liming the soil before you plant, and use more lime in the planting holes for any brassicas you plant. If you have White Rot that affects the allium (onion) family, it will manifest as white woolly mould around the bulbs..again, you won't know until you plant something..that one is nasty, you are supposed to wait 7 years before planting alliums in the same spot.
Work out a rotation plan so you are not going to be growing the same kinds of veg in the same place year after year, most people use a three or four year rotation at least, this will help minimise the risks of diseases building up in one area.
