need help choosing compatible components

[t_tberg]

So I recently bought a bike on craigslist only to find a crack in a swing arm linkage after Bowlofsalad pointed it out on a torque arm discussion form. So I've decided to take a different approach. I'm planning on buying a raw steel frame, something with the same specs as this:
https://www.randombikeparts.com/collections/frames-and-framesets/products/italian-raw-steel-19-mtb-bike-hardtail-frame-26-rim-brake-unpainted-new-2

Im planning on finding someone to weld some scrap steel to the dropouts to make some clamping style dropouts. I wont be using more than 3000 watts (at 74v) but I want the clamps because I plan on using regen. That won't be for a few weeks still, for now I'd like to order a fork and headset and handlebars that'll fit the frame I plan on buying with minimal modifications.

Bicycle building is still relatively new to me, so I'm not 100% certain what kind of hardware to buy.

The frame specs:

Head Tube: 3.75"
Head Tube Diameter: 33.75mm/38mm inner/outer

Can anyone suggest a combination of a fork (preferably a through axle), headset and handlebars, and a decent downhill wheel?
I'd like to keep the total cost for all of these items under $300.

 

[Drunkskunk]

Having that frame end up cracked sucks.

The frame you linked is a non suspension frame. If you put a suspension fork on the front, it's going to work poorly. The front will be too high, the angles will be all wrong, your seat will be too far up and back, your pedals too high off the ground, and you may not be stable.

The $76 version comes with a rigid fork, and looks like a good deal. Maybe not what you're after. You'll need a different frame.

The cheapest fork you should consider of DH quality is DNM. They suck compared to a real fork, but they are a good basic fork that will give you reliable operation and not get you killed. A through axle version runs $399. buying a prebuilt through-axle wheel runs ~$200. Getting a hub laced into your choice of DH rim could be done for ~$120-$150.
If you don't need through axle, you can probably find a working fork for the $150-200 range. the wheel could end up around $80-100. much depends on the frame you end up with.

 

[t_tberg]

One of my bikes is an older Schwinn Merida Sport with a 1000 watt ebay hub and a 48v 20ah battery, I was planing on upgrading the bike because it seems hard to find a good 1 inch threaded fork. The main reason I'd like to upgrade is to get a fork that allows for disc brakes. So I guess I could find a ridged fork with disc brakes and get wider hubs and tires.

 

[t_tberg]

I mean wider rims, running on hardly any sleep this finals week..