The geometry of bikes have evolved a lot from that time, but some of the lower end bikes of today still have that old geometry in some cases, using the old fixtures and tools. So it would depend on the bike. The fork might be the deal breaker if you can’t get new seals and if you don’t know how to fix it yourself it will cost some money to get serviced. You can buy cheap fork and though they are not awesome they are better than nothing. Used bikes are another option.
Often on forums questions like these are met with various responses of “you need to spend more”. I have been where you are, trying to get by feeling like you barely have two nickels to rub together. It is a struggle, to be sure. My kids are grown now and my mortgage is paid off. You will get through it. Resist the temptation to spend more than you should (not just with Bikes). It is OK to be out on the trail on whatever you can afford. Make the best of what you have and enjoy the woods. New bikes are awesome, but being out there is what you really need. Make the responsible decisions now and you will have the means to have awesome stuff later.