Not only is this unfortunately impossible with your current setup, it's impossible to reach a high overworld portal from the Nether as of 1.2.4:
As of the 1.2 update, there is a confirmed bug in which the "portal search" performed during travel back from the nether will not find any overworld portal above a height of 128. Thus, it is not possible to travel back to the overworld and land at a portal which is above y = 128.
From the Minecraft Wiki article.
Additionally, without mods, there is currently no way to move upwards without some sort of connecting structure, save perhaps a vertical TNT cannon, and it seems to me that you want something a bit more usable than that.
Now, in theory, once this bug is fixed, you could build a transport bridge a few blocks out in the Nether and the same number of block multiplied by 8 in the overworld coordinated just so that the higher platform is closer to the new portal, but it would be complex to do.
Until then, you're stuck with regular transportation.
The short answer is no. When You enter the a portal from the nether, on your way to the overworld, Minecraft calculates the primary portal coordinates with this generalized equation:
{X, Y, Z} → {floor(X) × 8, Y, floor(Z) × 8}
The game then checks for an active portal in a 128 block radius around that location. Given your nether portal coordinates:
X: -70; Y: 72; Z: -139
Your overworld portal must be within the following horizontal bounds:
X = -688, -432
Z = -1240, -984
Remember, any overworld portals within 1024 blocks of each other will link to the same nether portal, because 1024 blocks in the overworld = 128 blocks in the Nether, and the game checks for portals in a radius of 128 blocks.
If you build a new nether portal at the blaze farm and destroy your old portal, your main base portal will probably link up to your blaze farm. However, when you attempt to go back to the overworld, Minecraft will look for a portal within the above bounds and create a new one if it doesn't find one.
Your best option is probably to build a rail line from your current portal to the blaze farm. Ghasts can destroy any block with a blast resistance below 20.17, but they won't shoot at you without a line of sight, so you can make an inexpensive safety-tunnel around your rail line with pure Netherrack.
You can also build a more scenic tunnel with stone, glass, leaves, fences, etc, since Ghasts cannot "see" through transparent blocks.
Best Answer
Assuming you are using a texturepack (not the default Minecraft textures, ex Conquest of the Sun texture pack), and on a version 1.9 or higher.
In the texturepack .zip file, go to
And you'll find a portal.png file. Edit it to change the texture.
This file usually consists in several images stacked vertically, to be able to add an animation effect to the portal.
If you are using default Minecraft textures, you can find the textures_0.png (and following textures_1.png, 2, 3...) file in the following folder :
The portal texture is in around the middle, in the 17th column and 7th line.